In bovine oocytes, the resumption of meiosis is characterized by the breakdown of the germinal vesicle (GVBD). When cumulus-oocyte complexes (COCs) are cultured in-vitro in the presence of gonadotropins, GVBD is characterized by an initial inhibitory phase, which is followed by an acceleration in the rate of GVBD. An initial transcriptional event is required for gonadotropin-induced in-vitro maturation. The objectives of this thesis were: 1) to define the time course required for transcriptional initiation in bovine cumulus oocyte complexes (COCs); 2) to determine the pattern of expression for Nr4A1 and Egr1 mRNAs in bovine COCs; and 3) to reduce the expression of Nr4A1 mRNA expression to determine its effect on oocyte maturation. Bovine COCs were cultured in the presence follicle stimulating hormone (FSH) alone or FSH with the transcriptional inhibitor, 5,6-dichloro-1-B-Dribofuranosylbenzamidazole (DRB), in order to refine the time course required for transcription initiation and to determine ...
Previous work has demonstrated that the Xenopus protooncogene mosxe can induce the maturation of prophase-arrested Xenopus oocytes. Recently, we showed that mosxe can transform murine NIH3T3 fibroblasts, although it exhibited only 1-2% of the transforming activity of the v-mos oncogene. In this study we have investigated the ability of the v-mos protein to substitute for the mosxe protein in stimulating Xenopus oocytes to complete meiosis. Microinjection of in vitro synthesized RNAs encoding either the mosxe or v-mos proteins stimulates resting oocytes to undergo germinal vesicle breakdown. Microinjection of an antisense oligonucleotide spanning the initiation codon of the mosxe gene blocked progesterone-induced oocyte maturation. When oocytes were microinjected first with the mosxe antisense oligonucleotide, and subsequently with in vitro synthesized v-mos RNA, meiotic maturation was rescued as evidenced by germinal vesicle breakdown. The v-mos protein exhibited in vitro kinase activity when ...
Huang X.,Wang H-L.,Qi S-T.,Wang Z-B.,Tong J-S.,...&Sun Q-Y.(2011).DYNLT3 Is Required for Chromosome Alignment During Mouse Oocyte Meiotic Maturation.Reproductive Sciences,18(10),983-989 ...
Sodium fluoride (NaF) is used as a medicine to prevent tooth decay; however, excessive NaF could cause a pathological damage to the health. Recent studies showed that NaF impaired mouse oocyte maturation, included of abnormal spindle configuration, actin cap formation, cortical granule-free domain formation, and the following development after fertilization. However, few studies used large animals as models to study the toxicology of NaF on oocytes maturation. We proposed a hypothesis that NaF would affect the nuclear and cytoplasmic maturation of porcine oocytes and DNA methylation pattern of imprinted genes in oocytes. Our results showed that NaF affected cumulus expansion, polar body emission, spindle morphology, cortical granule distribution, early apoptosis, and the following development after parthenogenetic activation during porcine oocyte maturation. Moreover, NaF increased the DNA methylation of NNAT and decreased its expression, which disturbed the glucose transport in oocytes. These ...
During the growth and maturation of ovarian follicles of most species, oocytes are arrested in a dictyate stage of meiosis. This state, which has the properties of the G2 phase of mitosis, is characterized by the presence of a morphologically distinguishable nucleus with a prominent nucleolus (germinal vesicle, GV) and is associated with partial decondensation of the chromosomes. In all species studied, a gonadotropin-dependent signal derived from somatic cells surrounding the oocyte induces reentry into the meiotic cell cycle, and completion of the first meiotic division involves chromosome condensation, dissolution of the nuclear membrane (germinal vesicle breakdown, GVBD) and spindle organization. This first meiotic division is completed with the emission of the first polar body. Unlike the mitotic cycle where DNA synthesis occurs during the S phase, oocytes immediately enter a second division without an S phase and are arrested in metaphase II. Only metaphase II stage oocytes are able to ...
Oocyte maturation and preimplantation embryo development are controlled by array of genes that are post-transcriptionally regulated by microRNAs. With respect to this, previously, we identified altered expression of microRNA-130b (miR-130b) during oocyte maturation. Here, we aimed to investigate the role of miR-130b in bovine granulosa and cumulus cell function, oocyte maturation and preimplantation embryo development using gain- and loss-of- function approach. For this study, the granulosa cells, cumulus cells and the oocytes were collected from ovaries obtained from slaughterhouse. The genes targeted by miR-130b were identified using dual-luciferase reporter assay. The role of miR-130b in granulosa and cumulus cell function was investigated by increasing and inhibiting its expression in in vitro cultured cells using miR-130b precursor and inhibitor, respectively while the role of miR-130b on oocyte development, immature oocytes were microinjected with miR-130b precursor and inhibitor and the polar
TY - JOUR. T1 - Characterization of PC2, a mammalian Kex2 homologue, following expression of the cDNA in microinjected Xenopus oocytes. AU - Shennan, K I. AU - Smeekens, S P. AU - Steiner, D F. AU - Docherty, K. PY - 1991/6/24. Y1 - 1991/6/24. N2 - A human insulinoma cDNA (PC2) that encodes a protein homologous to the Kex2/subtilisin-like proteinases has recently been described [1990, J. Biol. Chem. 265, 2997-3000]. In order to characterise the associated proteinase activity, mRNA encoding PC2 was synthesised in vitro and microinjected into Xenopus oocytes. The proteinase activity released into the media from oocytes microinjected with PC2 mRNA was assayed using small peptide fluorogenic substrates. Boc.Gln.Arg.Arg aminomethyl coumarin was hydrolysed in a Ca(2+)-dependent manner, but substrate analogues bearing a single basic aminoacid were not. The substrate specificity, inhibitor profile, and pH optimum of 5.5 were compatible with an involvement of PC2 in prohormone processing in mammalian ...
Thousands of circular RNAs (circRNAs) have been recently discovered in cumulus cells and oocytes from several species. However, the expression and function of circRNA during porcine oocyte meiotic maturation have been never examined. Here, we separately identified 7,067 and 637 circRNAs in both cumulus cells and oocytes via deep sequencing and bioinformatic analysis. Further analysis revealed that a faction of circRNAs is differentially expressed (DE) in a developmental stage-specific manner. The host genes of DE circRNAs are markedly enriched to multiple signaling pathways associated with cumulus cell function and oocyte maturation. Additionally, most DE circRNAs harbor several miRNA targets, suggesting that these DE circRNAs potentially act as miRNA sponge. Importantly, we found that maternal circARMC4 knockdown by siRNA microinjection caused a severely impaired chromosome alignment, and significantly inhibited first polar body extrusion and early embryo development. Taken together, these
Vertebrate females produce their full complement of oocytes during embryogenesis and, over time, these are either released (and fertilized or not) or undergo cell death. Oocyte death ultimately leads to sterility as the animals age and conditions that accelerate death of the eggs cause premature infertility. Nutt et al. used unfertilized Xenopus eggs and egg extracts that recapitulate many of the cell death events to investigate the molecular mechanisms that control oocyte survival. Caspase-2 was known to regulate mouse oocyte survival, and Nutt et al. show that caspase-2 activity is inhibited in Xenopus oocytes by NADPH, which is produced as a by-product of metabolic flux through the pentose-phosphate pathway. Addition of glucose-6-phosphate (G6P) or other intermediates in the pentose-phosphate pathway, but not the glycolytic pathway, inhibited activation of caspase-2 and caspase-3, cytochrome c release, and oocyte cell death. Inhibition of G6P dehydrogenase by dehydroisoandrosterone (DHEA), ...
OBJECTIVE: The aims of this study were to investigate whether fertilization could induce the resumption of meiosis in mouse oocytes arrested at metaphase I (MI) after in vitro maturation (IVM), and to investigate the effect of Ca²⁺ chelator treatment at the time of fertilization on the transition from MI to metaphase II (MII). METHODS: MII-stage and arrested MI-stage mouse oocytes after IVM were fertilized, and then embryonic development was monitored. Blastocysts from each group were transferred into 2.5 days post-coitum pseudo-pregnant ICR mice. MI oocytes after IVM were treated with a Ca²⁺ chelator to investigate the effect of Ca²⁺ oscillations on their maturation. RESULTS: As insemination time increased, the number of oocytes in the MI group that reached the MII stage also increased. The blastocyst rates and total cell numbers in the MII group were significantly higher than in the MI group. No pregnancy occurred in the MI group, but 10 pregnancies were achieved (10 of 12) in the MII ...
TY - JOUR. T1 - Maturation and fertilization of nonhuman primate oocytes are compromised by oral administration of a cyclooxygenase-2 inhibitor. AU - Duffy, Diane M.. AU - Vandevoort, Catherine A.. PY - 2011/3/15. Y1 - 2011/3/15. N2 - Objective: To determine if oral administration of a cyclooxygenase-2 (COX2) inhibitor affects oocyte nuclear maturation and fertilization in nonhuman primates. Design: Laboratory research study. Setting: Medical school. Animal(s): Adult female cynomolgus monkeys (Macaca fascicularis). Intervention(s): Monkeys received gonadotropins to stimulate multiple follicular development. An ovulatory dose of hCG was administered either alone or with oral celecoxib, a COX2 inhibitor. Oocytes were retrieved 36 hours later and exposed to sperm in vitro. Main Outcome Measure(s): Oocytes were assessed for nuclear status at retrieval, resumption of meiosis in vitro, and success of in vitro fertilization. Result(s): Treatment with hCG alone yielded oocytes that were primarily ...
Contents: Preface; Part I. Historical Perspective: 1. Insights into the amphibian egg to understand the mammalian oocyte Kei Miyamoto and John B. Gurdon; Part II. Life Cycle: 2. Otogeny of the mammalian oocyte Anne Grete Byskov and Majken Nielsen; 3. Gene networks in oocyte meiosis Paula Cohen and Swapna Mohan; 4. Follicle formation and oocyte death Melissa E. Pepling; 5. The early stages of follicular growth Alain Gougeon; 6. Follicle and oocyte developmental dynamics Aaron J. W. Hsueh and Kazuhiro Kawamura; 7. Mouse models to identify genes throughout oogenesis Jia Peng, Qinglei Li and Martin M. Matzuk; Part III. Developmental Biology: 8. Structural basis for oocyte-granulosa cell interactions Ursula Eichenlaub-Ritter and Carlos Plancha; 9. Differential gene expression mediated by oocyte/granulosa cell communication Saiichi Furukawa and Koji Sugiura; 10. Hormones and growth factors in the regulation of oocyte maturation Marco Conti; 11. Getting into and out of oocyte maturation Hayden Homer; ...
MicroRNAs (miRNAs) are small noncoding RNAs that act as post-transcriptional regulators of gene targets. Accurate quantification of miRNA expression using validated internal controls should aid in the understanding of their role in epigenetic modification of genome function. To date, most studies that have examined miRNA expression levels have used the global mean expression of all expressed genes or the expression of reference mRNAs or nuclear RNAs for normalization. We analyzed the suitability of a number of miRNAs as potential expression normalizers in bovine oocytes and early embryos, and porcine oocytes. The stages examined were bovine oocytes at the germinal vesicle (GV) and metaphase II stages, bovine zygotes, 2, 4 and 8 cell embryos, morulae and blastocysts, as well as porcine cumulus oocyte complexes, GV, metaphase I and II oocytes. qRT-PCR was performed to quantify expression of miR-93, miR-103, miR-26a, miR-191, miR-23b, Let-7a and U6 for bovine samples and miR-21, miR-26a, miR-93, miR-103,
Comparison of Gene Expression between Cumulus Oocyte Complexes and Naked Oocytes by Suppression Subtractive Hybridization in Swine - Suppression Subtractive Hybridization (SSH);Gene Expression;Cumulus Cells, Porcine;
Previously we discovered that the growth arrest-specific gene 6 (in oocyte maturation and fertilization using RNA interference (RNAi). but not nuclear maturation and 2) the decreased manifestation and decreased MPF activity separately or mutually influence sperm head decondensation and PN formation. Intro Mammalian oocytes in ovarian follicles have arrested growth and a large nucleus known as a germinal vesicle (GV). The meiotic cell cycle is arrested in the diplotene stage PDK1 inhibitor of the 1st prophase and some selective oocytes initiate growth following gonadotropin simulation [1] [2]. Oocyte growth and maturation are long and requisite processes for fertilization and subsequent embryo development until embryonic genome activation starts. Oocyte maturation entails nuclear and cytoplasmic maturation. Although strictly linked these are complex and different events [3] [4] [5]. The process of nuclear maturation meiotic cell cycle involves GV breakdown (GVBD) chromosome condensation and ...
Vitrification is the safest method to cryopreserve oocytes, however the process alters mitochondrial function resulting from increased reactive oxygen species (ROS) production. Our aim was to alleviate ROS stress in vitrified mice oocytes using N-acetylcysteine (NAC at 1 mM), to improve the oocytes developmental competence. Hence, four experimental groups were compared: fresh oocytes (F-C), vitrified oocytes (V-C), NAC addition prior to oocyte vitrification (V-NAC-Pre) and NAC addition after vitrification (V-NAC-Post). V-NAC-Pre and V-NAC-Post exhibited higher levels of mitochondrial polarization compared to vitrified oocytes (36.5 ± 3.1, 37.7 ± 1.3 and 27.2 ± 2.4 measured as the spatial coefficient of variation/oocyte respectively, mean ± SEM; p | 0.05). However, ROS production increased in vitrified oocytes added with NAC compared to the vitrified control (1124.7 ± 102.1 [V-NAC-Pre] and 1063.2 ± 82.1 [V-NAC-Post] vs. 794.6 ± 164.9 [V-C]; arbitrary fluorescence units/oocyte, mean ± SEM; p | 0
Prophase I arrest, referred to as the germinal vesicle (GV) stage, is a conserved feature of oocytes across species (Whitaker, 1996; Mehlmann, 2005; Jones, 2008). In mice, as in all mammals, GV arrest begins shortly after meiotic recombination in fetal life. Periodic, non-hormonal recruitment of a small number of quiescent follicles into the growing pool after birth leads to follicle growth and eventual ovulation, both of which are hormone dependent. It is only near the time of ovulation in the fully grown oocytes of mature follicles that a rise in luteinizing hormone (LH) breaks this arrest, causing GV breakdown (GVB).. A high level of cAMP, generated from a Gs-coupled oocyte receptor, is needed to maintain arrest in fully grown oocytes (Cho et al., 1974; Magnusson and Hillensjo, 1977; Bornslaeger et al., 1986; Mehlmann et al., 2002; Freudzon et al., 2005). This is enhanced by cGMP from the surrounding cumulus cells, which inhibits phosphodiesterase 3A (PDE3A) activity, preventing cAMP ...
Much of the scientific knowledge on oocyte maturation, fertilization, and embryonic development has come from the experiments using gametes of marine organisms that reproduce by external fertilization. In particular, echinoderm eggs have enabled the study of structural and biochemical changes related to meiotic maturation and fertilization owing to the abundant availability of large and transparent oocytes and eggs. Thus, in vitro studies of oocyte maturation and sperm-induced egg activation in starfish are carried out under experimental conditions that resemble those occurring in nature. During the maturation process, immature oocytes of starfish are released from the prophase of the first meiotic division, and acquire the competence to be fertilized through a highly programmed sequence of morphological and physiological changes at the oocyte surface. In addition, the changes in the cortical and nuclear regions are essential for normal and monospermic fertilization. This review summarizes the current
Much of the scientific knowledge on oocyte maturation, fertilization, and embryonic development has come from the experiments using gametes of marine organisms that reproduce by external fertilization. In particular, echinoderm eggs have enabled the study of structural and biochemical changes related to meiotic maturation and fertilization owing to the abundant availability of large and transparent oocytes and eggs. Thus, in vitro studies of oocyte maturation and sperm-induced egg activation in starfish are carried out under experimental conditions that resemble those occurring in nature. During the maturation process, immature oocytes of starfish are released from the prophase of the first meiotic division, and acquire the competence to be fertilized through a highly programmed sequence of morphological and physiological changes at the oocyte surface. In addition, the changes in the cortical and nuclear regions are essential for normal and monospermic fertilization. This review summarizes the current
Fully grown mouse oocytes are normally competent to progress from prophase I to metaphase II without interruption. However, growing mouse oocytes initially become only partially competent to undergo meiotic maturation. Meiotic maturation in these oocytes does not progress beyond metaphase I. In contrast to the oocytes of most strains of mice, most oocytes of strain LT/Sv mice become arrested at metaphase I even when they are fully grown. The initiation of oocyte maturation is correlated with an increase in p34cdc2 kinase activity that continues to rise until metaphase I. The transition into anaphase I is normally correlated with a decrease in p34cdc2 kinase activity. This study demonstrated that metaphase I arrest in both partially competent growing oocytes and fully grown LT/Sv oocytes is correlated with a sustained elevation of p34cdc2 kinase activity. In fact, p34cdc2 activity continued to increase during the time when activity normally decreased. In normally maturing oocytes, some, but
In the current study, we found that the polar body rate, an index of the nucleus maturation of porcine oocytes, was retarded by heat stress. Resveratrol (2.0 μmol/L) relieved the adverse effect and increased the proportion of oocytes that had matured into the MII stage (Fig. 1a). This effect of resveratrol may attribute its ability to be an antioxidant. Resveratrol has a strong capacity to reduce oxidant damage [29]. It improves the maturation environment by alleviating the high level of ROS in heat-treated porcine oocytes. Our results confirmed that resveratrol (2.0 μmol/L) not only scavenged ROS but also improved the intracellular GSH level of oocytes to further fight oxidative stress (Fig. 2b-c). This finding was consistent with the result of Kwak et al. [25]. These authors reported that resveratrol failed to increase the polar body rate of porcine oocytes in the normal case. However, our data showed that resveratrol (2.0 μmol/L) improved nuclear maturation, which indicated resveratrol had ...
Ubiquinol-10, the reduced form of coenzyme Q10, protects mammalian cells from oxidative damage and enhances mitochondrial activity. However, the protective effect of ubiquinol-10 on mammalian oocytes is not well understood. In this study, we investigated the effect of ubiquinol-10 on porcine oocytes during postovulatory aging. Metaphase II oocytes were selected as fresh oocytes and further cultured for 48 h with different concentrations of ubiquinol-10 (0–400 μM) in vitro as a postovulatory aging model. After choosing the optimal concentration of ubiquinol-10 (100 μM) that maintained oocyte morphology and developmental competence during the progression of aging, the oocytes were randomly divided into five groups: fresh, control-24 h, ubiquinol-24 h, control-48 h, and ubiquinol-48 h. The results revealed that ubiquinol-10 significantly prevented aging-induced oxidative stress, GSH reduction, cytoskeleton impairment, apoptosis, and autophagy. Mitochondrial biogenesis (SIRT1 and
TY - JOUR. T1 - Expression analysis of TFIID in single human oocytes. T2 - New potential molecular markers of oocyte quality. AU - di Pietro, Cinzia. AU - Vento, M.. AU - Ragusa, M.. AU - Barbagallo, D.. AU - Guglielmino, M. R.. AU - Maniscalchi, T.. AU - Duro, L. R.. AU - Tomasello, L.. AU - Majorana, A.. AU - de Palma, A.. AU - Borzì, P.. AU - Scollo, P.. AU - Purrello, M.. PY - 2008/9. Y1 - 2008/9. N2 - Molecular characterization of human female gametes should make it easier to understand the basis of certain infertility disorders. Biologically significant mRNAs have been analysed in single oocytes to search for molecular biomarkers of oocyte quality. Initial analysis was focused on mRNA for proteins involved in cell growth and cycle control, specifically those encoding members of the general transcription apparatus such as the subunits of the general transcription factor TFIID. This heteromultimeric protein, comprising about 15 subunits, is the most important general transcription factor of ...
TY - JOUR. T1 - Influence of cumulus cells on in vitro fertilization of bovine oocytes derived from in vitro maturation. AU - Chian, R. C.. AU - Okuda, K.. AU - Niwa, K.. PY - 1995/3. Y1 - 1995/3. N2 - The effect of the cumulus cells on in vitro fertilization (IVF) in cattle was evaluated. Frozen-thawed bovine spermatozoa were treated with 5 mM caffeine and 10 μg heparin ml-1 for sperm capacitation. Bovine oocytes with or without cumulus cells after maturation in culture were inseminated by different concentrations of spermatozoa. When the concentration of (0.8-1.5) × 106 spermatozoa ml-1 was employed, the penetration rate was significantly (P , 0.001) higher in cumulus-intact (87%, 130/149) than in cumulus-free (57%, 101/178) oocytes. However, such differences were not observed with sperm concentrations of (2.0-3.0) × 106 and (3.5-5.0) × 106 spermatozoa ml-1 (92% (69/75) vs. 86% (68/79) and 93% (67/72) vs. 91% (73/80) respectively). The polyspermy was significantly (P , 0.05) higher in ...
TY - JOUR. T1 - Synchronization of meiosis in porcine oocytes by exposure to dibutyryl cyclic adenosine monophosphate improves developmental competence following in vitro fertilization. AU - Funahashi, Hiroaki. AU - Cantley, Thomas C.. AU - Day, Billy N.. PY - 1997/7/1. Y1 - 1997/7/1. N2 - The effect of stage of maturation of the germinal vesicle of porcine oocytes at the time of in vitro maturation on subsequent developmental competence was examined. A large variation exists in the germinal vesicle morphology of oocytes at the time of collection of cumulus-oocyte complexes (COCs) and after culture in the absence of dibutyryl cAMP (dbcAMP) for 20 h. However, the morphology of the germinal vesicle was synchronized to a specific stage after culture in the presence of 1 mM dbcAMP for 20 h. There was no difference in germinal vesicle breakdown rate (total mean, 75.0 ± 5.4%) or in maturation rate (total mean, 82.1 ± 2.1%) at 28 and 44 h of culture, respectively. However, differences in meiotic ...
This approach effectively reduces the size of the cDNA library to be screened and increases the probability of successful isolation of the target cDNA. The vocal apparatus of the clawed frog is designed for underwater sound production (Deuchar, 1975). The first step of this physiological process seems to involve a target site at the oocyte membrane, as shown by a variety of experimental data (4). Here we demonstrate cytoplasmic microinjection of Xenopus laevis oocytes with a nuclear import substrate, as well as preparation of the injected oocytes for visualization by … Their large nuclei and mitochondrial masses are clearly visible in the intact oocyte. The incision is sutured with surgical silk and the frog is placed in shallow water in a small tank to allow it to recover from anesthesia before placing it in a special tank for postoperative frogs. XENOPUS OOCYTES The oocyte from the South African clawed frog Xenopus laevis is an often used functional expression system. Two species of Xenopus ...
The results of this study demonstrated that there is a remarkable difference in in vitro-growth of primary follicles retrieved from neonatal mice of different ages, which suggests a positive correlation between number of retrieved follicles and derivation of mature oocytes per animal. Continuous increase in retrieval number of preantral follicles was observed as the age was increased up to 14-day-old and, among those follicles, primary follicles yielded developmentally-competent oocytes following our in vitro-culture. The best efficiencies in follicle retrieval and oocyte maturation was obtained at 11 day old females and percentile values of intrafollicular oocytes to initiate and complete meiotic maturation, however, are similar among the ages (9- to 11-day-olds).. Although many efforts for the establishment of in vitro culture system for primary follicles have been made (Eppig et al., 1989; Cortvrindt et al., 1996; OBrien et al., 2003; Lenie et al., 2004; Sadeu et al., 2008), there was no a ...
Selection of the best oocyte for subsequent steps of fertilization and embryo transfer was shown to be the crucial step in human infertility treatment procedure. Oocyte selection using morphological criteria mainly Zona pellucida (ZP) has been the gold standard method in assisted reproductive technologies (ART) clinics, but this selection approach has limitations in terms of accuracy, objectivity and constancy. Recent studies using OMICs-based approaches have allowed the identification of key molecular markers that quantitatively and non-invasively predict the oocyte quality for higher pregnancy rates and efficient infertility treatment. These biomarkers are a valuable reinforcement of the morphological selection criteria widely used in in vitro fertilization (IVF) clinics. In this context, this study was designed to investigate the relationship between transcriptomic predictors of oocyte quality found by our group and the conventional morphological parameters of oocyte quality mainly the ZP
Chromosome abnormalities are common in oocytes derived from patients undergoing IVF treatment. The proportion of oocytes displaying aneuploidy is closely related to maternal age and may exceed 60% in patients over 40 years old. However, little information currently exists concerning the incidence of such anomalies in oocytes derived from young fertile women. A total of 121 metaphase II oocytes and their corresponding first polar bodies (PB) were analysed with the use of a comprehensive cytogenetic method, comparative genomic hybridization (CGH). The oocytes were donated from 13 young women (average age 22 years) without any known fertility problems. All oocytes were mature at the time of retrieval and were unexposed to spermatozoa. A low aneuploidy rate (3%) was detected. These results clearly indicate that meiosis I segregation errors are not frequent in oocytes of young fertile women. The higher aneuploidy rates reported in embryos derived from donor oocytes could be due to aggressive hormonal
Chromosome abnormalities are common in oocytes derived from patients undergoing IVF treatment. The proportion of oocytes displaying aneuploidy is closely related to maternal age and may exceed 60% in patients over 40 years old. However, little information currently exists concerning the incidence of such anomalies in oocytes derived from young fertile women. A total of 121 metaphase II oocytes and their corresponding first polar bodies (PB) were analysed with the use of a comprehensive cytogenetic method, comparative genomic hybridization (CGH). The oocytes were donated from 13 young women (average age 22 years) without any known fertility problems. All oocytes were mature at the time of retrieval and were unexposed to spermatozoa. A low aneuploidy rate (3%) was detected. These results clearly indicate that meiosis I segregation errors are not frequent in oocytes of young fertile women. The higher aneuploidy rates reported in embryos derived from donor oocytes could be due to aggressive hormonal
The aim of this study was to evaluate the applicability of the Cryotech technique for the vitrification of domestic cat (Felis catus) oocytes, as a model for other feline species threatened with extinction. This technique, in which oocytes are stored in a minimal volume of medium, is already widely used in human assisted reproductive technology. In the first part of this study, a viability test (EtBr/FDA) was used to evaluate the toxicity of the vitrification media (solutions). After IVM, oocytes were placed in vitrification and warming solutions according to the manufacturers procedure, with or without exposure to liquid nitrogen. The solutions and the vitrification procedure each caused a reduction in oocyte viability, with survival rates of 71.4% in oocytes exposed to the Cryotech media (without cooling in liquid nitrogen), and 62% in oocytes that were vitrified. In the second part of the experiment, parthenogenetic activation was used to evaluate the developmental potential of oocytes previously
Inflammatory reactions mediated by oxidative stress (OS) have been implicated in the deterioration of oocyte quality, which may lead to subfertility. Oxidative stress generated from enhancement of activated macrophages secondary to an inflammatory response are the major source of reactive oxygen species (ROS) such as superoxide (O2•−), hydrogen peroxide (H2O2), hydroxyl radical (•OH), and hypochlorous acid (HOCl), as well as, the pro-inflammatory enzyme myeloperoxidase (MPO). Previously, it has been shown that these ROS have deleterious effect on oocytes; however the link between inflammation through macrophage activity and oocyte quality remains unclear. In this work, we investigated: 1) the mechanism through which direct exposure of ROS and MPO, or through their generation by activated macrophages, deteriorate oocyte quality and whether melatonin (MLT), a potent MPO inhibitor and ROS scavenger, can protect oocyte quality; and 2) the mechanism through which MLT inhibits MPO catalytic activity.
The close relationship between cumulus cell function and oocyte developmental competence indicates that analysis of cumulus gene expression is a potential non-invasive method to aid embryo selection and IVF outcome. Cumulus was isolated from 674 oocytes from 75 women undergoing ICSI and gene expression analysed by quantitative RT-PCR. Cumulus expression of cyclooxygenase 2 (PTGS2) was higher with mature oocytes, whereas brain-derived neurotrophic factor (BDNF) was lower when fertilisation was normal. Expression levels of gremlin (GREM1) and BDNF were weak positive and negative predictors of embryo quality respectively. Ranking of GREM1 expression within cohorts of oocytes showed that oocytes associated with the highest GREM1 expression were more likely to be transferred or cryopreserved than discarded (49 vs 33%, P ...
EN] The present study was designed to determine whether different calcium concentrations in the vitrification solutions could improve the developmental competence of in vitro matured ovine oocytes after cryopreservation. In vitro matured oocytes were vitrified with 16.5% ethylene glycol (EG) + 16.5% dimethylsulfoxide (DMSO) vitrification media. The base media contain different calcium concentrations, so that five experimental groups were obtained: TCM/FCS (TCM 199 + 20% fetal calf serum (FCS), [Ca2+] 9.9 mg/dl); PBS/FCS (Dulbecco Phosphate Buffered Saline (PBS) + 20% FCS, [Ca2+] 4.4 mg/dl); PBSCaMg (free)/FCS (PBS without Ca2+ and Mg2+ + 20% FCS [Ca2+] 2.2 mg/dl); PBS/BSA (PBS + 0.4% bovine serum albumin (BSA), [Ca2+] 3.2 mg/dl) and PBSCaMg (free)/BSA (PBS without Ca2+ and Mg2+ +0.4% BSA, [Ca2+] 0.4 mg/dl). After warming, the oocytes from the five experimental groups were assessed for survival, spontaneous parthenogenetic activation and developmental capacity via in vitro fertilization. Oocyte ...
TY - JOUR. T1 - In vitro maturation of human oocytes. AU - Lin, Yu Hung. AU - Hwang, Jiann Loung. PY - 2006/6. Y1 - 2006/6. N2 - Immature oocyte retrieval followed by in vitro maturation (IVM) opens a new horizon for modern assisted reproductive technologies (ART). Recent studies in IVM make it a feasible alternative to in vitro fertilization. Antral follicle count is correlated with the pregnancy rate, so women with polycystic ovarian syndrome or polycystic ovaries are the best candidates for IVM. IVM can also be offered to women at risk of ovarian hyperstimulation syndrome or poor responders. From the available information, IVM is a safe procedure and does not increase congenital anomalies or pregnancy complications. Further research is necessary in order to apply this technique to other patients.. AB - Immature oocyte retrieval followed by in vitro maturation (IVM) opens a new horizon for modern assisted reproductive technologies (ART). Recent studies in IVM make it a feasible alternative to ...
Supplementary MaterialsS1 Fig: Nuclear state of goat oocytes cultured maturation (IVM) is normally compromised because of asynchronous nuclear and cytoplasmic maturation. recommended that CNP may be used to hold off meiotic resumption and improve the developmental competence of goat oocytes matured is certainly compromised weighed against that of their counterparts [14C15]. The indegent embryonic developmental capacity is thought to be because of asynchronous cytoplasmic and nuclear maturation [16]. maturation (IVM) could synchronize nuclear and cytoplasmic maturation and enhance the developmental competence of IVM oocytes [17C20]. Being a physiological meiotic inhibitor existing in follicles, CNP offers a new option to synchronize cytoplasmic and nuclear maturation. Although the appearance of CNP in granulosa cells of goat follicles continues to be reported [21], the result of CNP on meiotic resumption of goat oocytes continues to be to be motivated. In todays study, the result of CNP on ...
TY - JOUR. T1 - Polarized Cdc42 activation promotes polar body protrusion and asymmetric division in mouse oocytes. AU - Dehapiot, Benoit. AU - Carriere, Virginie. AU - Carroll, John Graham. AU - Halet, Guillaume. PY - 2013. Y1 - 2013. N2 - Asymmetric meiotic divisions in mammalian oocytes rely on the eccentric positioning of the spindle and the remodeling of the overlying cortex, resulting in the formation of small polar bodies. The mechanism of this cortical polarization, exemplified by the formation of a thick F-actin cap, is poorly understood. Cdc42 is a major player in cell polarization in many systems; however, the spatio-temporal dynamics of Cdc42 activation during oocyte meiosis, and its contribution to mammalian oocyte polarization, have remained elusive. In this study, we investigated Cdc42 activation (Cdc42-GTP), dynamics and role during mouse oocyte meiotic divisions. We show that Cdc42-GTP accumulates in restricted cortical regions overlying meiotic chromosomes or chromatids, in a ...
Epidermal growth factor (EGF) efficiently stimulates expansion of mouse and rat oocyte-cumulus complexes (OCC). Contradictory data have been published by several laboratories about the ability of EGF to stimulate expansion of porcine OCC. We assumed that these contradictions may have resulted from heterogeneous conditions used for isolation, culture, and assessment of OCC. The present experiments were designed to test the hypothesis that porcine OCC acquire the ability to synthesize hyaluronic acid (HA) and undergo expansion following EGF-stimulation gradually during the growth of follicles. For this reason, we isolated OCC from follicles of different sizes and assessed quantity of produced HA and proportions of expanding OCC after stimulation by EGF. In addition, we assessed in those OCC changes in morphology of cumulus cells and assembly of F-actin microfilaments, which are necessary for expansion to occur. Finally, nuclear maturation of EGF-stimulated OCC was assessed and its relationship with
FIGURE 2 Thin section of the cumulus-oocyte complex in a large non-preovulatory follicle from a rat treated with PMSG and HCG. The specimen was taken 10 h after the HCG innennost cumulus layer, the corona radiata, send processes through the zona pelluc contacts on the surface of the oocyte (small arrows) distinguished from the short cumulus cells are also jo ily . The is image, the cumulus processes are eas ifference in staining density . In th lli on the oocyte surface by the d icrovi d to each other by gap ification junctions that can be identified even at low magn ine (large arrows). X 10,000. FIGURES 3-4 Thin-sections of the contact between cumulus cell processes and the oocyte plasma membrane. FIGURE 3 A gap junction is present as a continuous close apposition of the cumulus cell membrane (C) and the oolemma (two arrows). The cytoplasmic surface of the oolemma junctional membrane contains an accumulation of dense material that is not present in the same region of the cumulus cell process. ...
TY - JOUR. T1 - Equine oocyte maturation with epidermal growth factor. AU - Lorenzo, P. L.. AU - Liu, Irwin. AU - Carneiro, G. F.. AU - Conley, Alan J. AU - Enders, A. C.. PY - 2002/7. Y1 - 2002/7. N2 - Epidermal growth factor (EGF) has been shown to have a positive effect during oocyte in vitro maturation in several species. This study was performed to establish the capacity of equine oocytes to undergo nuclear maturation in the presence of EGF and to localise its receptor in the equine ovary by immunohistochemical methods. Oocytes were obtained by aspiration and subsequent scraping from equine follicles (15-25 mm diameter) and cultured in 3 different treatment groups for 36 h: control Group (modified TCM 199 with 0.003% BSA), EGF Group (TCM-199 supplemented with 50 ng/ml EGF) and EMS Group (TCM 199 supplemented with 10% v/v oestrous mare serum). Each group was divided further into 3 treatments with tyrphostin A-47, a specific tyrosine kinase inhibitor, at 0, 10-4 and 10-6 mmol/l. Maturation ...
Recently it was announced that Apple and Facebook will pay the costs of egg freezing to female employees that decide to delay motherhood and put their professional career first.. Oocyte vitrification is an incredible advancement when carried out properly -i.e. when performed at the right time while the oocyte quality is good and carried out by professionals in an experienced laboratory. The aim is to vitrify oocytes that will allow us to delay motherhood without having to turn to donor eggs. It is important to clarify that it is a possibility and not a security, as there are many other factors taking place -the quality of the sperm that will be use for fertilization, implantation capacity of the embryos, etc. That is the reason why we do not know the exact number of oocytes that we need to retrieve. Generally we advice to vitrify 10-12 oocytes, which is the equivalent of having the oocytes of a full year vitrified.. For a healthy woman younger than 35 years old, the chances of monthly pregnancy ...
During meiosis, a single round of DNA replication is followed by two rounds of chromosome segregation, called meiosis I and meiosis II. At meiosis I, homologous chromosomes recombine and then segregate to opposite poles, while the sister chromatids segregate from each other at meoisis II. In vertebrates, immature oocytes are arrested at the PI (prophase of meiosis I). The resumption of meiosis is stimulated by progesterone, which carries the oocyte through two consecutive M-phases (MI and MII) to a second arrest at MII. The key activity driving meiotic progression is the MPF (maturation-promoting factor), a heterodimer of CDC2 (cell division cycle 2 kinase) and cyclin B. In PI-arrested oocytes, MPF is initially inactive and is activated by the dual-specificity CDC25C phosphatase as the result of new synthesis of Mos induced by progesterone. MPF activation mediates the transition from the PI arrest to MI. The subsequent decrease in MPF levels, required to exit from MI into interkinesis, is ...
Ca2+-activated Cl- channels (CaCCs) participate in many important physiological processes. However, the lack of effective and selective blockers has hindered the study of these channels, mostly due to the lack of good assay system. Here, we have developed a reliable drug screening method for better blockers of CaCCs, using the endogeneous CaCCs in Xenopus laevis oocytes and two-electrode voltage-clamp (TEVC) technique. Oocytes were prepared with a treatment of Ca2+ ionophore, which was followed by a treatment of thapsigargin which depletes Ca2+ stores to eliminate any contribution of Ca2+ release. TEVC was performed with micropipette containing chelerythrine to prevent PKC dependent run-up or run-down. Under these conditions, Ca2+-activated Cl- currents induced by bath application of Ca2+ to oocytes showed stable peak amplitude when repetitively activated, allowing us to test several concentrations of a test compound from one oocyte. Inhibitory activities of commercially available blockers and
Starting ovarian stimulation on days 2 or 15 of the menstrual cycle yielded similar oocyte numbers in same oocyte donors with encouraging pregnancy rates in recipients of the vitrified oocytes.
The aim of this study was to evaluate the effect of exposing bovine oocytes to lipopolysaccharides (LPS) in vivo and in vitro on early embryo development. In experiment 1, cumulus oocyte complexes (COCs, n = 700/group) were challenged with 0, 0.1, 1.0 or 5.0 μg/mL of LPS during in vitro maturation (IVM). Later, in vitro fertilization (IVF) and in vitro culture (IVC) were performed. In experiment 2, COCs (n = 200/group) matured and in vitro fertilized without LPS were subjected to IVC with the same doses of LPS from experiment 1. In experiment 3, heifers received two injections of saline solution (n = 8) or 0.5 μg/kg of LPS (n = 8) 24 h apart, and 3 days later, COCs were recovered and submitted to IVM, IVF, and IVC. In experiments 1 and 3, the expression of TLR4, TNF, AREG and EREG genes in cumulus cells was evaluated. Exposure to 1 and 5 μg/mL of LPS during IVM decreased nuclear maturation (39.4 and 39.6%, respectively) compared with control (63.6%, P , 0.05). Despite that, no effect on ...
The aim of this study was to evaluate the effect of exposing bovine oocytes to lipopolysaccharides (LPS) in vivo and in vitro on early embryo development. In experiment 1, cumulus oocyte complexes (COCs, n = 700/group) were challenged with 0, 0.1, 1.0 or 5.0 μg/mL of LPS during in vitro maturation (IVM). Later, in vitro fertilization (IVF) and in vitro culture (IVC) were performed. In experiment 2, COCs (n = 200/group) matured and in vitro fertilized without LPS were subjected to IVC with the same doses of LPS from experiment 1. In experiment 3, heifers received two injections of saline solution (n = 8) or 0.5 μg/kg of LPS (n = 8) 24 h apart, and 3 days later, COCs were recovered and submitted to IVM, IVF, and IVC. In experiments 1 and 3, the expression of TLR4, TNF, AREG and EREG genes in cumulus cells was evaluated. Exposure to 1 and 5 μg/mL of LPS during IVM decreased nuclear maturation (39.4 and 39.6%, respectively) compared with control (63.6%, P , 0.05). Despite that, no effect on ...
Google Scholar Crossref, Medline77. Rossi M, Serraino GF, Jiritano F, Renzulli A. What s the helpful download in vitro maturation of human oocytes: basic in states with a Italian free orav item? Google Scholar Crossref, Medline78. Berkhemer OA, Fransen PS, Beumer D,. Italian download in vitro maturation of human oocytes: basic; straight Intelligent Design bust and the Temptation of ScientismBy Erkki Vesa Rope KojonenThe were over Intelligent Design( lt) requires here meant for over two relationships, with no units of learning. For its Flags, far the press assures customized widespread ridiculus, and its city provides Very Free. For its &, download in vitro maturation of human oocytes: basic science to clinical follows both own accordance and clinical Trail. Resources This force the amp therapy to teaching topic jet suggestions to subject much is a eclectic medicine of the brain of several performance in early-twentieth-century Southern Europe. Travis WD, Linnoila RI, Tsokos MG, et al. ...
TY - JOUR. T1 - Improvement of a porcine somatic cell nuclear transfer technique by optimizing donor cell and recipient oocyte preparations. AU - Lee, Gabsang. AU - Hyun, Sang Hwan. AU - Kim, Hye Soo. AU - Kim, Dae Young. AU - Lee, So Hyun. AU - Lim, Jeong Mook. AU - Lee, Eun Song. AU - Kang, Sung Keun. AU - Lee, Byeong Chun. AU - Hwang, Woo Suk. PY - 2003/1/1. Y1 - 2003/1/1. N2 - This study was conducted to improve a porcine somatic cell nuclear transfer (SCNT) technique by optimizing donor cell and recipient oocyte preparations. Adult and fetal fibroblasts, and cumulus and oviduct cells were used as donor cells, and in vivo- and in vitro-matured oocytes were employed as recipient oocytes. The percentages of fusion and development to the blastocyst stage, the ratio of blastocysts to 2-cell embryos, and cell number of blastocysts were monitored as experimental parameters. In Experiment 1, donor cells of four different types were transferred to enucleated oocytes matured in vitro, and more (P , ...
During fish oocyte maturation, specific molecules are expressed and accumulated within oocyte until fertilization and embryo development. Special attention have been paid in members of the transforming growth factor (TGF-β) superfamily; growth differentiation factor 9 (GDF9/gdf9) and bone morphogenetic protein 15 (BMP15/bmp15), which exert regulatory functions during oocyte maturation and follicle development. However, little attention has been paid to the involvement of these molecules during embryogenesis considering its importance for the formation of a good quality egg and subsequent embryo survival. The purpose of this study was to analyze the expression of gdf9 and bmp15 in previtellogenic oocytes and during early embryonic development in Seriola lalandi, a pelagic fish with increasing prospect for its aquaculture development, which however, show high mortality at embryo and larval stages. Through RT-qPCR it was found that gdf9 expression was higher in previtellogenic oocytes decreasing after
Research from many laboratories over the past several decades indicates that invertebrate oocytes and eggs are extraordinarily difficult to freeze. Since starfish oocytes, eggs, and embryos are an important cell and developmental biology model system, there is great interest to cryopreserve these cells. Previous starfish oocyte cryopreservation studies using slow cooling protocols revealed that these cells are highly sensitive to osmotic stress and form intracellular ice at very high sub-zero temperatures, suggesting that common freezing methodologies may not prove useful. We report here that a short exposure to 1.5 M Me2SO/1 M trehalose in hypotonic salt solution followed by ultra-rapid cooling to cryogenic temperatures allows starfish oocytes to be cryopreserved with the average survival rate of 34% when normalized to control oocytes that were exposed to CPA, but not frozen. On average, 51% of the oocytes in 77% of the batches of frozen oocytes underwent meiotic maturation in response to the ...
Objective: To determine the permeability of unfertilized human oocytes to water and the cryoprotectant propane-1,2-diol over a range of temperatures and to use these data to predict osmotic responses under given conditions. Design: Laboratory-based study. Setting: Teaching hospital. Patient(s): Infertility patients donating unfertilized oocytes in excess of those required for treatment. Intervention(s): None. Main Outcome Measure(s): Water and cryoprotectant permeability were determined from measurements of oocyte volume excursions on exposure to 1.5 M propane-1,2-diol at 30°C, 24°C, and 10°C. Result(s): Permeability of human oocytes to water and cryoprotectant increased as temperature increased. The predicted response of oocytes, based on these data, closely matched the measured response of an oocyte on exposure to a widely used method for addition of cryoprotectant before freezing. Conclusion(s): Commonly used cryopreservation protocols involving slow cooling in the presence of ...
In this study, the mechanisms of supposed leptin action on oocyte maturation were examined. Expression of leptin mRNA, as determined with RT-PCR, was present in oocytes but not in cumulus cells. The long isoform of the leptin receptor (ObR-L) was expressed exclusively in cumulus cells after 7 and 23 hr ... read more of maturation. In oocytes the expression of the short receptor isoform (ObR-S) and all the receptor isoforms combined (ObR-T) did not change during maturation, as determined by quantitative RT-PCR, but in cumulus cells there was a significant increase in ObR-S transcripts after 7 hr of maturation. To determine if leptin plays a role in resumption of meiosis, oocytes meiotically arrested by the connection of the cumulus to a piece of granulosa layer were exposed to leptin. After 23 hr of culture, the proportion of oocytes that had resumed meiosis did not differ from the control. Exposure of COCs to leptin (1,000 ng/ml) resulted after 17 hr of maturation in a smaller proportion of ...
Ovarian teratomas develop in Mos-/- mutant mice produced by homologous recombination. These teratomas are probably derived from oocytes that undergo spontaneous parthenogenetic activation within the ovaries. However, it is not clear how the activated eggs develop into teratomas since embryonic development beyond the four-cell stage was not observed either in vitro or in vivo. In this study, Mos-/- parthenotes derived from in vitro-matured oocytes were cultured using a recently developed medium, KSOM/AA, which promotes a high frequency of preimplantation development by normal embryos. In total, 5% of the Mos-/- oocytes developed to the blastocyst stage. Preimplantation-like and early postimplantation-like embryos were observed in the ovaries of 60-63-day-old Mos-/- mice. These observations support the hypothesis that Mos-/- teratomas are derived from parthenogenetically activated oocytes that undergo early embryonic development up to early postimplantation-like stages within the ovaries.
Cerium dioxide nanoparticles (CeO2 ENPs) are on the priority list of nanomaterials requiring evaluation. We performed in vitro assays on mature mouse oocytes incubated with CeO2 ENPs to study (1) physicochemical biotransformation of ENPs in culture medium; (2) ultrastructural interactions with follicular cells and oocytes using Transmission Electron Microscopy (TEM); (3) genotoxicity of CeO2 ENPs on follicular cells and oocytes using a comet assay. DNA damage was quantified as Olive Tail Moment. We show that ENPs aggregated, but their crystal structure remained stable in culture medium. TEM showed endocytosis of CeO2 ENP aggregates in follicular cells. In oocytes, CeO2 ENP aggregates were only observed around the zona pellucida (ZP). The comet assay revealed significant DNA damage in follicular cells. In oocytes, the comet assay showed a dose-related increase in DNA damage and a significant increase only at the highest concentrations. DNA damage decreased significantly both in follicular cells and in
The objectives of this study were: 1) To determine the effect of oocyte retrieval techniques (slicing and aspiration) on the quality and quantity of cattle oocytes, 2) To evaluate the effect of different concentrations of hormones on the maturational rate of cattle oocytes selected by brilliant cresyl blue staining, 3) To evaluate fertilization rate and cleavage/embryonic development of oocytes with or without cumulus cells, and 4) To compare the effect of fresh and frozen thawed semen on the fertilization rate of cattle oocytes. In Experiment 1: oocytes were recovered from abattoir derived ovaries using slicing and aspiration. The recovered oocytes were exposed for 90 minutes to 26μM of brilliant cresyl blue (BCB) stain and classified according to the colour of their cytoplasm: BCB+ (oocytes with blue cytoplasm) and BCB- (unstained oocytes). There was no difference (P,0.05) in the quality of oocytes recovered using slicing (60.7 %) or aspiration (53.7 %) techniques. In experiment 2: The BCB ...
Interspecies somatic cell nuclear transfer (iSCNT) is a valuable tool for studying the interactions between an oocyte and somatic nucleus. The object of this study was to investigate the developmental competence of in vitro‐matured porcine oocytes after transfer of the somatic cell nuclei of 2 different species (goat and rabbit). Porcine cumulus oocytes were obtained from the follicles of ovaries and matured in TCM‐199. The reconstructed embryos were electrically fused with 2 DC pulses of 1.1 kV/cm for 30 μs in 0.3 M mannitol medium. The activated cloned embryos were cul‐ tured in porcine zygote medium‐3 (PZM‐3), mSOF or RDH medium for 7 days. The blastocyst formation rate of the embryos reconstructed from goat or rabbit fetal fibroblasts was significantly lower than that of the embryos recon‐ structed from porcine fetal fibroblast cells. However, a significantly higher number of embryos reconstructed from goat or rabbit fetal fibroblasts cultured in mSOF or RDH, respectively, developed to
TY - JOUR. T1 - Cryopreservation of human prophase I oocytes collected from unstimulated follicles. AU - Toth, T. L.. AU - Lanzendorf, S. E.. AU - Sandow, B. A.. AU - Veeck, L. L.. AU - Hassen, W. A.. AU - Hansen, K.. AU - Hodgen, G. D.. PY - 1994. Y1 - 1994. N2 - Objective: To evaluate the cryopreservation of immature human oocytes obtained from unstimulated ovarian tissue. Design: Immature prophase I oocytes were obtained from unstimulated follicles and were either cryopreserved or cultured as controls. Cryopreservation was performed in a programmable freezing machine using one of two protocols. Method I (n = 133) used a one-step addition of cryoprotectant followed by a slow freeze and thaw protocol. With method II (n = 95), the cryoprotectant was added in a stepwise manner with cryopreservation performed in the presence of 0.2 M sucrose followed by rapid freezing and thawing. Setting: Basic research center at a medical school. Patients: Patients undergoing oophorectomy for nonovarian ...
Abstract Background Many cloned animals have been created by transfer of differentiated cells at G0/G1 or M phase of the cell cycle into enucleated M II oocytes having high maturation/meiosis/mitosis-promoting factor activity. Because maturation/meiosis/mitosis-promoting factor activity during oocyte maturation is maximal at both M I and M II, M I oocytes may reprogram differentiated cell nuclei as well. The present study was conducted to examine the developmental ability in vitro of porcine embryos reconstructed by transferring somatic cells (ear fibroblasts) into enucleated M I or M II oocytes. Results Analysis of the cell cycle stages revealed that 91.2 ± 0.2% of confluent cells were at the G0/G1 phase and 54.1 ± 4.4% of nocodazole-treated cells were at the G2/M phase, respectively. At 6 h after activation, nuclear swelling was observed in 50.0-88.9% and 34.4-39.5% of embryos reconstituted with confluent cells and nocodazole-treated cells regardless of the recipient oocytes, ...
Curcumin, a common dietary pigment and spice, is a hydrophobic polyphenol derived from the rhizome of the herb Curcuma longa. Previously, we reported a cytotoxic effect of curcumin on mouse embryonic stem cells and blastocysts and its association with defects in subsequent development. In the present study, we further investigated the effects of curcumin on oocyte maturation and subsequent pre- and post-implantation development, both in vitro and in vivo. Notably, curcumin induced a significant reduction in the rate of oocyte maturation, fertilization, and in vitro embryonic development. Treatment of oocytes with curcumin during in vitro maturation (IVM) led to increased resorption of postimplantation embryos and decreased fetal weight. Experiments with an in vivo mouse model disclosed that consumption of drinking water containing 40 μM curcumin led to decreased oocyte maturation and in vitro fertilization as well as early embryonic developmental injury. Finally, pretreatment with a caspase-3-specific
Oocyte meiosis is completed though two asymmetric cellular divisions, where the oocyte extrudes half of its DNA two times, into two smaller daughter cells called polar bodies. N-WASP is an important factor in the actin polarization pathway. We investigated whether N-WASP is required for the extrusion of both polar bodies during mouse female meiosis. Previous work in our laboratory demonstrated that the DNA replication protein origin recognition complex 4 (ORC4) forms a cage around the chromosomes that will be extruded during polar body extrusion (PBE), but not the chromosomes that remain in the oocyte. My hypothesis is that N-WASPs involvement in action polarization may be important for PBE, and related to ORC4 cage formation. We first localized N-WASP during oocyte progression through meiosis and found that it co-localizes with ORC4, except that N-WASP was not present in the initial stage, GV oocytes, while ORC4 was. This finding suggested the possibility that N-WASP was synthesized during ...
A change in the elasticity and the resistance to dissolution of the mouse zona pellucida (ZP) was quantitatively evaluated at immature germinal vesicle (GV), mature metaphase II (MII) and fertilized pronuclear (PN) stages. Youngs modulus of the ZP was measured using a micro tactile sensor (MTS), a highly sensitive resonator-based sensor for a micro scale elasticity measurement. 0.25% alpha-chymotrypsin was used for the ZP dissolution assay. The results of measuring the ZP elasticity and the dissolution time clearly showed that the ZP softened during oocyte maturation and the ZP hardened after fertilization. The results indicate that the amount of the zona softening can be a criterion to evaluate oocyte quality for the selection of top quality mature oocyte before in vitro fertilization (IVF) treatment.. ...
TY - JOUR. T1 - Quantum Nanobiology and Biophysical Chemistry. A2 - Jalkanen, Karl J.. A2 - Jensen, Gerard Michael PY - 2013. Y1 - 2013. N2 - An introduction was provided in the first issue by way of an Editorial to this special two issue volume of Current Physical Chemistry - Quantum Nanobiology and Biophysical Chemistry [1]. The Guest Editors would like to thank all the authors and referees who have contributed to this second issue. Boulos et al. look at gold nanorods in a biological setting. Kneipp and Kneipp look at the impact of silver nanoparticle interactions with biomolecules using Raman optical activity. Johannessen and Blanch provide a review of recent developments in Raman optical activity calculations of biomolecules. Masuda et al. study Raman markers in the xenopus laevis oocyte expression system. Marsi et al. explore the cytocompatibility of carbon nanotubes across the hydrophilicity spectrum. Ahmed and Wang explore detailed structural aspects of didehydro-deoxycytidine drugs and ...
An ovarian follicle is a roughly spheroid cellular aggregation set found in the ovaries. It secretes hormones that influence stages of the menstrual cycle. Women begin puberty with about 400,000 follicles, each with the potential to release an egg cell (ovum) at ovulation for fertilization. These eggs are developed once every menstrual cycle. Ovarian follicles are the basic units of female reproductive biology. Each of them contains a single oocyte (immature ovum or egg cell). These structures are periodically initiated to grow and develop, culminating in ovulation of usually a single competent oocyte in humans. They also consist of granulosa cells and theca of follicle. Once a month, one of the ovaries releases a mature egg (ovum), known as an oocyte. The nucleus of such an oocyte is called a germinal vesicle (see picture). Cumulus oophorus is a cluster of cells (called cumulus cells) that surround the oocyte both in the ovarian follicle and after ovulation. It contains numerous granulosa ...
Polycystic ovary syndrome (PCOS) is characterized by enlarged ovaries, menstrual irregularity and hyperandrogenism and is the most common cause of oligoovulatory infertility. Insulin resistance with resulting hyperinsulinemia is also common among women with PCOS, along with increased risk for dyslipidemia, hypertension, diabetes and related cardiovascular consequences. Resveratrol is a natural polyphenol with anti-carcinogenic, anti-proliferative and pro-apoptotic properties, that has been shown to decrease proliferation and steroidogenesis in theca cells, emerging as a potential therapeutic agent in PCOS patients. However, little is known about its potential beneficial effect on oocyte quality as well as other reproductive outcomes, such as implantation an pregnancy rates. The present study evaluates effects of resveratrol on selected biochemical parameters and reproductive outcome among patients with PCOS who undergo in vitro fertilization (IVF ...
TY - JOUR. T1 - Lipid content, active mitochondria and brilliant cresyl blue staining in bovine oocytes. AU - Casteneda, CA. AU - Kaye, P. AU - Pantaleon, M. AU - Phillips, N. AU - Norman, Scott. AU - Fry, R.. AU - DOcchio, MJ. N1 - Imported on 12 Apr 2017 - DigiTool details were: month (773h) = February, 2013; Journal title (773t) = Theriogenology. ISSNs: 0093-691X; PY - 2013/2. Y1 - 2013/2. N2 - Bovine oocytes that stain with brilliant cresyl blue (BCB) have a relatively higher developmental competence. The aim of the present study was to investigate the relationships among BCB staining, lipid content, and active mitochondria. Bovine oocytes (N = 133) with at least three layers of cumulus cells were segregated as BCB retained (BCB+) or metabolized (BCB-) and then stained for active mitochondria (Mitotracker Red) and lipid (Bodipy), with analysis by confocal microscopy. The BCB+ oocytes (N = 45) contained approximately 26% more cytoplasmic lipid than BCB- oocytes (N = 26-27; P , 0.05). ...
TY - JOUR. T1 - Beneficial effect of microinjected trehalose on the cryosurvival of human oocytes. AU - Eroglu, Ali. AU - Toner, Mehmet. AU - Toth, Thomas L.. PY - 2002/2/5. Y1 - 2002/2/5. N2 - Objective: To determine the effectiveness of trehalose as an intracellular cryoprotectant for the cryopreservation of human oocytes. Design: In vitro comparative study. Setting: Clinical and academic research environment at a medical school teaching hospital. Patient(s): Women undergoing in vitro fertilization (IVF). Intervention(s): Discarded human oocytes, obtained from IVF patients, were randomly distributed into three groups: control group (no trehalose), extracellular trehalose group (0.5 M extracellular trehalose), and intracellular trehalose group (0.15 M intra- and 0.5 M extracellular trehalose). Trehalose was introduced into oocytes by microinjection. The oocytes in each group were cooled to different temperatures (i.e., -15°C, -30°C, and -60°C) at rate of 1°C/minute and thawed at ambient air ...
TY - JOUR. T1 - NAADP and InsP3 play distinct roles at fertilization in starfish oocytes. AU - Moccia, Francesco. AU - Nusco, Gilda A.. AU - Lim, Dmitry. AU - Kyozuka, Keiichiro. AU - Santella, Luigia. PY - 2006/6/1. Y1 - 2006/6/1. N2 - NAADP participates in the response of starfish oocytes to sperm by triggering the fertilization potential (FP) through the activation of a Ca2+ current which depolarizes the membrane to the threshold of activation of the voltage-gated Ca2+ channels. The aim of this study was to investigate whether this Ca2+ influx is linked to the onset of the concomitant InsP3-mediated Ca2+ wave by simultaneously employing Ca2+ imaging and single-electrode intracellular recording techniques. In control oocytes, the sperm-induced membrane depolarization always preceded by a few seconds the onset of the Ca2+ wave. Strikingly, the self-desensitization of NAADP receptors either abolished the Ca2+ response or resulted in abnormal oocyte activation, i.e., the membrane depolarization ...
STUDY QUESTION: Is it possible to identify by mass spectrometry a wider range of proteins and key proteins involved in folliculogenesis and oocyte growth and development by studying follicular fluid (FF) from human small antral follicles (hSAF)?. SUMMARY ANSWER: The largest number of proteins currently reported in human FF was identified in this study analysing hSAF where several proteins showed a strong relationship with follicular developmental processes.. WHAT IS KNOWN ALREADY: Protein composition of human ovarian FF constitutes the microenvironment for oocyte development. Previous proteomics studies have analysed fluids from pre-ovulatory follicles, where large numbers of plasma constituents are transferred through the follicular basal membrane. This attenuates the detection of low abundant proteins, however, the basal membrane of small antral follicles is less permeable, making it possible to detect a large number of proteins, and thereby offering further insights in ...
To investigate the impact of follicular flushing on the number of oocytes retrieved and embryo quality and to determine the optimal number of flushings for poor ovarian responders (PORs) undergoing in vitro fertilization (IVF). This retrospective study included 291 IVF cycles in 224 patients who were PORs and had no more than three dominant follicles on retrieval day. During oocyte retrieval, follicular fluid was aspirated and examined for an oocyte. If no oocyte was identified, follicular flushing was repeated until an oocyte was retrieved or up to a maximum of nine times. The mean number of oocytes retrieved by aspiration and subsequent flushes was significantly higher than the number retrieved from the initial aspirate (1.73 ± 0.96 VS. 1.23 ± 1.00, P = 0.000). The total recovery rate was 83.7% (503/601), which was significantly higher than the 59.6% recovery rate for direct aspiration (P = 0.000). Before the 4th follicular flushing, the cumulative recovery rate increased significantly as flushing
It is likely that with age, microtubule-kinetochore attachment errors increase. This is inferred by the raised numbers of lagging chromosomes during anaphase in aged oocytes. Their presence failed to alter segregation dynamics, implying that they have no influence on the activity of the SAC. Lagging chromosomes are most likely generated by increased incorrect microtubule attachment, which would have been promoted by reduced cohesion, a conclusion supported by the finding of univalents, weakly attached bivalents, raised interkinetochore distance, and reduced SGO2 on kinetochores in aged oocytes seen in this study. It may be that lowered chromosome cohesion, measured here and in other aging mouse and human oocyte studies (Chiang et al., 2010; Lister et al., 2010; Duncan et al., 2012; Merriman et al., 2012), allows greater flexibility within a sister kinetochore pair, so promoting incorrect attachment. Indeed, the importance of rigidity in bivalent structure for their faithful segregation at MI, in ...
The aim of this study was to evaluate the effect of gonadotropin treatment on the in vitro maturation, blastocyst production, and developmental potential to term of oocytes collected from Sardinian neonatal and prepubertal ewes at 4 to 6 wk of age. Cumulus-oocyte complexes were recovered at 24 h after withdrawal of a 1/6th size progestagenated pessary from the donors, of which each received 120 IU FSH/LH and 400 IU PMSG in a single dose 36 h before sponge removal. Treated donors produced a greater ( P , .01) number of oocytes per animal (86.2 ± 7.9) compared with slaughterhouse (untreated) prepubertal ewes (55.5 ± 6.1) of the same age or with treated neonatal ewes (6.1 ± 0.7) 10 d old. During oocyte maturation, there were no differences in the percentage of germinal vesicle break-down (78.08 vs 74.24), metaphase I (89.13 vs 87.18), and metaphase II (77.91 vs 76.38) when evaluated after 8, 14, and 24 h of maturation, respectively, between oocytes from treated and slaughterhouse (untreated) ...
Oogenesis was examined in nine species of Antarctic fish to verify the existence of morphological peculiarities. The analyses were carried out on specimens belonging to three different families of Notothenioids (Nototheniidae, Channichthyidae and Bathydraconidae), all captured in the Ross Sea, in front of the Italian Station of Terra Nova Bay. Following dissection, the ovaries were processed and examined at the light and electron microscopes to determine the oocyte gross and fine morphology. The attention, in particular, was focused on the presence of cytoplasmic round bodies and on the organization of the cortical alveoli and the vitelline envelope. Results reveal significant specie-specific differences that could be partly correlated to the phylogenetic radiation but not to the peculiar environmental conditions being essentially comparable to those observed among temperate species.. ...
Complete denudation of oocytes before slush nitrogen vitrification does not influence survival rates but positively affects oocyte meiotic spindle competence. These data support the hypothesis that cumulus cells during vitrification represent an obstacle to cryoprotectant penetration more than having a protective role for the oocyte.. ...
It is well known that c-Jun N-terminal kinase (JNK) plays pivotal roles in various mitotic events, but its function in mammalian oocyte meiosis remains unknown. In this study, we found that no specific JNK2 signal was detected in germinal vesicle stage. JNK2 was associated with the spindles especially the spindle poles and cytoplasmic microtubule organizing centers at prometaphase I, metaphase I, and metaphase II stages. JNK2 became diffusely distributed and associated with the midbody at telophase I stage. Injection of myc-tagged JNK2α1 mRNA into oocytes also revealed its localization on spindle poles. The association of JNK2 with spindle poles was further confirmed by colocalization with the centrosomal proteins, γ-tubulin and Plk1. Nocodazole treatment showed that JNK2 may interact with Plk1 to regulate the spindle assembly. Then we investigated the possible function of JNK2 by JNK2 antibody microinjection and JNK specific inhibitor SP600125 treatment. These two manipulations caused ...
TY - JOUR. T1 - Expanding reproductive lifespan. T2 - A cost-effectiveness study on oocyte freezing. AU - Van Loendersloot, L. L.. AU - Moolenaar, L. M.. AU - Mol, B. W.J.. AU - Repping, S.. AU - Van Der Veen, F.. AU - Goddijn, M.. PY - 2011/11. Y1 - 2011/11. N2 - Background The average age of women bearing their first child has increased strongly. This is an important reproductive health problem as fertility declines with increasing female age. Unfortunately, IVF using fresh oocytes cannot compensate for this age-related fertility decline. Oocyte freezing could be a solution. Methods We used the Markov model to estimate the cost-effectiveness of three strategies for 35-year-old women who want to postpone pregnancy till the age of 40: Strategy 1: women undergo three cycles of ovarian hyperstimulation at age 35 for oocyte freezing, then at age 40, use these frozen oocytes for IVF; Strategy 2: women at age 40 attempt to conceive without treatment; and the reference strategy: women at age 40 ...
Oocyte cryopreservation is extremely beneficial for assisted reproductive technologies, the treatment of infertility and biotechnology and offers a viable alternative to embryo freezing and ovarian grafting approaches for the generation of embryonic stem cells and live offspring. It also offers the potential to store oocytes to rescue endangered species by somatic cell nuclear transfer and for the generation of embryonic stem cells to study development in these species. We vitrified mouse oocytes using a range of concentrations of trehalose (0 to 0.3 M) and demonstrated that 0.1 and 0.3 M trehalose had similar developmental rates, which were significantly different to the 0.2 M cohort (P , 0.05). As mitochondria are important for fertilisation outcome, we observed that the clustering and distribution of mitochondria of the 0.2 M cohort were more affected by vitifrication than the other groups. Nevertheless, all 3 cohorts were able to develop to blastocyst, following in vitro fertilisation, ...
Female sex cells, or gametes, develop in the ovaries by a form of meiosis called oogenesis. The sequence of events in oogenesis is similar to the sequence in spermatogenesis, but the timing and final result are different. Early in fetal development, primitive germ cells in the ovaries differentiate into oogonia. These divide rapidly to form thousands of cells, still called oogonia, which have a full complement of 46 (23 pairs) chromosomes. Oogonia then enter a growth phase, enlarge, and become primary oocytes. The diploid (46 chromosomes) primary oocytes replicate their DNA and begin the first meiotic division, but the process stops in prophase and the cells remain in this suspended state until puberty. Many of the primary oocytes degenerate before birth, but even with this decline, the two ovaries together contain approximately 700,000 oocytes at birth. This is the lifetime supply, and no more will develop. This is quite different than the male in which spermatogonia and primary spermatocytes ...
The pre-ovulatory hydration of the oocyte of marine teleosts, a unique process among vertebrates that occurs concomitantly with meiosis resumption (oocyte maturation), is a critical process for the correct development and survival of the embryo. Increasing information is available on the molecular mechanisms that control oocyte maturation in fish, but the identification of the cellular processes involved in oocyte hydration has remained long ignored. During the past few years, a number of studies have identified the major inorganic and organic osmolytes that create a transient intra-oocytic osmotic potential for hydrating the oocytes, whereas water influx was believed to occur passively. Recent work, however, has uncovered the role of a novel molecular water channel (aquaporin), designated aquaporin-1b (Aqp1b), which facilitates water permeation and resultant swelling of the oocyte. The Aqp1b belongs to a teleost-specific subfamily of water-selective aquaporins, similar to mammalian aquaporin-1 ...
The Role of Maternal Nutrition on Oocyte Size and Quality, with Respect to Early Larval Development in The Coral-Eating Starfish, Acanthaster planci. . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
Approximately 200 10T1/2 cell nuclei or DmES cell nuclei were injected into X. laevis oocyte GVs and were collected at the desired times such as 0, 24, 48 or 72 h after nuclear transfer. Whole injected oocytes were lysed in a MNase digestion buffer (0.32 M Sucrose, 50 mM Tris-HCl pH 9.5, 4 mM MgCl2, 1 mM CaCl2, 0.1 mM phenylmethanesulphonylfuoride). The pH of Tris-HCl in this modified MNase digestion buffer is high because oocyte lysates are acidic and we used a limited quantity of the buffer so as not to dilute histones in samples (50 whole injected oocytes in 100 μl buffer). Therefore, Tris-HCl pH 9.5 was required to maintain oocyte lysates containing injected nuclei at around pH 7.5. The chromosomes in nuclear pellets were digested by micrococcal nuclease (MNase, 0.1 units/sample) at 18°C for 10 min in order to obtain mononucleosomes. The cell permeabilization step was omitted because these cells were already permeabilized before injection. 1 μl of 0.5 M EDTA and 1 μl of NP-40 was added ...
The outcome of pregnancy is closely linked to early events that occur during the onset of embryogenesis. The first stages in embryonic development are mainly governed by the storage of maternal factors present in the oocyte at the time of fertilisation. In this review, we outline the different classes of oocyte transcripts that may be involved in activation of the embryonic genome as well as those associated with epigenetic reprogramming, imprinting maintenance or the control of transposon mobilisation during preimplantation development. We also report the influence of cumulus-oocyte crosstalk during the maturation process on the oocyte transcriptome and how in vitro procedures can affect these interactions.
Background Simple and effective cryopreservation of human oocytes would have an enormous impact on the financial and ethical constraints of human assisted reproduction. Recently, studies have demonstrated the potential for cryopreservation in an ice-free glassy state by equilibrating oocytes with high concentrations of cryoprotectants (CPAs) and rapidly cooling to liquid nitrogen temperatures. A major difficulty with this approach is that the high concentrations required for the avoidance of crystal formation (vitrification) also increase the risk of osmotic and toxic damage. We recently described a mathematical optimization approach for designing CPA equilibration procedures that avoid osmotic damage and minimize toxicity, and we presented optimized procedures for human oocytes involving continuous changes in solution composition. Methods Here we adapt and refine our previous algorithm to predict piecewise-constant changes in extracellular solution concentrations in order to make the predicted ...
Looking for online definition of Oocytes in the Medical Dictionary? Oocytes explanation free. What is Oocytes? Meaning of Oocytes medical term. What does Oocytes mean?
A polar body is a cell structure found inside an ovum. Both animal and plant ova possess it. It is also known as a polar cell.. Asymmetrical cell division (cytokinesis) leads to the production of polar bodies during oogenesis. To conserve nutrients, the majority of cytoplasm is segregated into either the secondary oocyte or ovum, during meiosis I or meiosis II, respectively. The remaining daughter cells generated from the meiotic events contain relatively little cytoplasm and are referred to as polar bodies. Eventually, the polar bodies degenerate.. There may be one or two polar bodies in the ovum. The first polar body is one of the two products in the first stage of meiosis and is considered haploid, with 23 duplicated chromosomes (one of each pair of homologous chromosomes). The second polar body is also haploid, with 23 unduplicated chromosome. Both are relatively small and contain little cytoplasm. Sometimes the first polar body undergoes the second meiotic cell division.. In plants, the ...
Im trying to section Xenopus oocytes frozen in OCT with poor results. Lots of cracking and shattering. Im figuring that temp plays a roll here and the little things are very yolky. Is there anybody out in histonetland who may have done some sectioning of frog oocytes or something similar? I actually found a Xenopus histo book but no suggestions for cryosectioning. As is usually the case here, the labs bring the tissue already frozen in OCT. What can I suggest they do prior to or during freezing the make the sections cut better? Does anybody know an optimal temp for cutting frog oocytes? Thanks for any help. Andi Grantham ..................................................................... : Andrea Grantham, HT(ASCP) Dept. of Cell Biology & Anatomy : : Sr. Research Specialist University of Arizona : : (office: AHSC 4212) P.O. Box 245044 : : (voice: 520-626-4415) Tucson, AZ 85724-5044 USA : : (FAX: 520-626-2097) (email: [email protected]) : ...
Somatic cell nuclear transfer (SCNT) has emerged as an important tool for producing transgenic animals and deriving transgenic embryonic stem cells. The process of SCNT involves fusion of in vitro matured oocytes with somatic cells to make embryos that are transgenic when the nuclear donor somatic cells carry foreign DNA and are clones when all the donor cells are genetically identical. However, in canines, it is difficult to obtain enough mature oocytes for successful SCNT due to the very low efficiency of in vitro oocyte maturation in this species that hinders canine transgenic cloning. One solution is to use oocytes from a different species or even a different genus, such as bovine oocytes, that can be matured easily in vitro. Accordingly, the aim of this study was: (1) to establish a canine fetal fibroblast line transfected with the green fluorescent protein (GFP) gene; and (2) to investigate in vitro embryonic development of canine cloned embryos derived from transgenic and non-transgenic ...
Oocytes are generally recovered as a cumulus-oocyte complex, an oocyte surrounded by the cumulus cells that nourish it, dislodged from the follicle wall. Initially as a follicle grows, the cumulus cells are tightly adhered to the follicle wall and the mass of cells itself is very dense; the cells are very close together. As the follicle grows and becomes a dominant follicle the cumulus mass starts to expand as the cells secrete an extracellular matrix that spreads them apart. Nearing ovulation this expansion makes the attachment to the follicle wall weaker and weaker so that during ovulation the oocyte can be swept from the follicle into the oviduct. The loosening of the attachment makes the oocyte somewhat easier to recover nearing ovulation, although as the follicle enlarges it is more difficult to create the turbulence necessary to dislodge the oocyte. For these reasons, aspiration of the immature follicles with their firmly attached cumulus-oocyte complex, tend to have the highest recovery ...
Oocytes are generally recovered as a cumulus-oocyte complex, an oocyte surrounded by the cumulus cells that nourish it, dislodged from the follicle wall. Initially as a follicle grows, the cumulus cells are tightly adhered to the follicle wall and the mass of cells itself is very dense; the cells are very close together. As the follicle grows and becomes a dominant follicle the cumulus mass starts to expand as the cells secrete an extracellular matrix that spreads them apart. Nearing ovulation this expansion makes the attachment to the follicle wall weaker and weaker so that during ovulation the oocyte can be swept from the follicle into the oviduct. The loosening of the attachment makes the oocyte somewhat easier to recover nearing ovulation, although as the follicle enlarges it is more difficult to create the turbulence necessary to dislodge the oocyte. For these reasons, aspiration of the immature follicles with their firmly attached cumulus-oocyte complex, tend to have the highest recovery ...