Background: Vitrification of oocytes is a fast-freezing technique, which may affect the quality of the human oocyte, and consequently affects the embryo development, pregnancy and birth. The aim of the current study was to investigate the consequence of in-vitro vitrification on maturation status of immature human oocytes, additionally, expression levels of stress, and apoptosis related genes. Materials and Methods: The total of 213 human immature oocytes which routinely discarded from assisted reproduction clinics were collected and divided into two groups including: (I) fresh germinal vesicle (GV) oocytes (n=106) (matured in-vitro  (fIVM) , and  (II) GV oocytes (n=107) that initially vitrified, then matured in  in-vitro (vIVM). After 36 hours of incubation, the oocytes were evaluated for nuclear maturation and expression level of DNA methyltransferase (DNMT1), stress related genes (Sod1 and Hsp70), and apoptotic related genes (Bax and Bcl-2) by quantitative Real-Time ...
TY - JOUR. T1 - Microtubular spindle dynamics and chromosome complements from somatic cell nuclei haploidization in mature mouse oocytes and developmental potential of the derived embryos. AU - Chen, Shee Uan. AU - Chang, Chia Yi. AU - Lu, Chien Cheng. AU - Hsieh, Fon Jou. AU - Ho, Hong Nerng. AU - Yang, Yu Shih. PY - 2004/1/1. Y1 - 2004/1/1. N2 - Background: The aim of this study was to investigate haploidization of somatic cell nuclei in non-enucleated mature oocytes regarding spindle formation, chromosomes and developmental potential. Methods: Mouse cumulus cells were injected into metaphase II oocytes. Some injected oocytes were examined for morphological changes of chromosomes and the spindle immediately, and at 30 min, 1 h or 2 h after the injections. The remaining oocytes were activated by Sr 2+ after various incubation periods and observed for formation of a second polar body and pseudo-polar body. Cytogenetic analysis was performed for some of the resulting zygotes. The progress to ...
TY - JOUR. T1 - Tryptophan Inhibits the [3H]Glutamate Uptake into Xenopus Oocytes Injected with Rat Brain mRNA. AU - Tohda, Michihisa. AU - Urushihara, Hisashi. AU - Nomura, Yasuyuki. PY - 1992/1. Y1 - 1992/1. N2 - We characterized the glutamate (Glu) uptake in Xenopus oocytes injected with rat brain mRNA. The Glu uptake into oocytes was higher in mRNA-injected oocytes than in vehicle-injected ones. Na+ omission or addition of tryptophan inhibited the uptake in mRNA-injected oocytes, although it did not affect that in vehicle-injected oocytes. These results suggest that Glu transporters with a tryptophan sensitivity different from that of Glu transporters in native oocytes are expressed after injection of rat brain mRNA.. AB - We characterized the glutamate (Glu) uptake in Xenopus oocytes injected with rat brain mRNA. The Glu uptake into oocytes was higher in mRNA-injected oocytes than in vehicle-injected ones. Na+ omission or addition of tryptophan inhibited the uptake in mRNA-injected oocytes, ...
The divisions of the germline stem cell are asymmetric in that they generate a renewing cell and a cell with the capacity to differentiate as an oocyte. Thereafter, the asymmetric meiotic divisions of oocytes produce one large cell, the egg, and two small polar bodies. In addition to asymmetric divisions, asymmetries are present in the form of localized cellular structures, organelles (mitochondria, endoplasmic reticulum, the oocyte nucleus), and also in the distribution of proteins and RNAs within the oocyte. All or a subset of these asymmetries are present in nearly all animals (Figure 3). For example, in most animals, the nucleus is in a central position within the early oocyte, but as oogenesis progresses, the oocyte nucleus moves to the oocyte periphery, or cortex (Figure 3). The side of the cell where the oocyte nucleus is localized in late-stage vertebrate oocytes is generally defined as the animal pole (Figure 3). Earlier asymmetries in oocytes are also shared among animals.
Prolonged culture of metaphase II oocytes is an in vitro aging process that compromises oocyte quality. We tested whether melatonin preserves epigenetic modifications in oocytes after prolonged culture. The porcine oocytes were maturated in vitro for 44 h, and then metaphase II oocytes were continuously cultured in medium supplemented with or without melatonin for 24 h. We found that the parthenogenetic blastocyst formation rate of prolonged-culture oocytes was lower than in fresh oocytes. We further observed that methylation at H3K4me2 and H3K27me2 of oocytes enhanced after prolonged culture. However, 5mc fluorescence intensity was lower in prolonged-culture oocytes than in fresh oocytes. Moreover, the promoter of the imprinted gene NNAT exhibited a higher level of DNA methylation in prolonged-culture oocytes than in fresh oocytes, which was associated with a reduced expression level and glucose uptake capability. Conversely, melatonin improved blastocyst formation rate and
Prolonged culture of metaphase II oocytes is an in vitro aging process that compromises oocyte quality. We tested whether melatonin preserves epigenetic modifications in oocytes after prolonged culture. The porcine oocytes were maturated in vitro for 44 h, and then metaphase II oocytes were continuously cultured in medium supplemented with or without melatonin for 24 h. We found that the parthenogenetic blastocyst formation rate of prolonged-culture oocytes was lower than in fresh oocytes. We further observed that methylation at H3K4me2 and H3K27me2 of oocytes enhanced after prolonged culture. However, 5mc fluorescence intensity was lower in prolonged-culture oocytes than in fresh oocytes. Moreover, the promoter of the imprinted gene NNAT exhibited a higher level of DNA methylation in prolonged-culture oocytes than in fresh oocytes, which was associated with a reduced expression level and glucose uptake capability. Conversely, melatonin improved blastocyst formation rate and
TY - JOUR. T1 - Exogenous adenosine Reduces the mitochondrial membrane potential of murine oocytes during the latter half of in vitro maturation and pronuclear formation following chemical activation. AU - Fujii, Wataru. AU - Funahashi, Hiroaki. PY - 2009/5/13. Y1 - 2009/5/13. N2 - The present study was undertaken to determine the effect of nucleosides on nuclear and cytoplasmic maturation of mouse oocytes. Oocyte-cumulus complexes (OCCs) were collected from large antral follicles 4 h after eCG-hCG treatment and cultured in maturation medium with or without nucleosides (4 ribo- and 4 deoxyribonucleosides) for 12 h. A majority of the oocytes examined developed to the metaphase-II stage, and the same result was found with in-vivo matured oocytes. However, mitochondrial membrane potential (MMP) was significantly lower in the oocytes matured in the presence of nucleosides than in the nucleoside-free controls. Oocyte MMP increased in vivo between 8 to 12 h after hCG injection, whereas no increases in ...
TY - JOUR. T1 - Effect of incubation with different concentrations and durations of FSH for in-vitro maturation of murine oocytes. AU - Lin, Yu Hung. AU - Hwang, Jiann-Loung. AU - Seow, Kok Min. AU - Huang, Lee Wen. AU - Hsieh, Bih Chwen. AU - Chen, Hen Ju. AU - Tzeng, Chii Ruey. AU - Bai, Chyi Huey. PY - 2011/7. Y1 - 2011/7. N2 - The purpose of the study was to evaluate whether a lower concentration of FSH or 2-h incubation with FSH would improve the outcome of in-vitro maturation of oocytes. The immature oocytes were obtained from FVB mice, and were allocated to four groups and incubated in the maturation media for 24 h. The maturation media were supplemented with 10 mIU/ml FSH for 24 h (group 1), 10 mIU/ml FSH for 2 h (group 2), 75 mIU/ml FSH for 24 h (group 3) or 75 mIU/ml FSH for 2 h (group 4). In each group, half of the in-vitro-matured oocytes were fertilized and cultured to blastocysts and the remaining matured oocytes were analysed for growth differentiation factor (GDF)-9 and bone ...
Synonyms for primary oocyte in Free Thesaurus. Antonyms for primary oocyte. 1 word related to oocyte: gametocyte. What are synonyms for primary oocyte?
Meiosis in mammalian oocytes is driven by changes in the activity of maturation-promoting factor (MPF). MPF activity is attributed entirely to the activity of the universal mitotic kinase, cdk1-cyclin B (Draetta et al., 1989; Labbe et al., 1989; Gautier et al., 1990). In mammals, oocytes are arrested in prophase of meiosis I with low levels of MPF (Hashimoto and Kishimoto, 1986; Choi et al., 1991). An increase in MPF activity stimulates entry into M phase of meiosis I, the first sign of which is germinal vesicle (GV) breakdown (GVBD), which takes place ∼90 min after release from the follicle. Continued cyclin B synthesis and increasing levels of MPF drive the oocyte to metaphase of the first meiotic division (Tay et al., 2000; Ledan et al., 2001), which is followed by polar body extrusion 7-9 h after GVBD. After MI, the oocyte proceeds immediately to meiosis II, where it arrests with high levels of MPF activity that are stabilized by cytostatic factor (CSF; Masui and Markert, 1971; Hashimoto ...
RNA binding proteins play a pivotal role during the oocyte-to-embryo transition and maternal phase of embryogenesis in invertebrates, but their function in these processes in mammalian systems remain largely understudied. Here we report that a member of the Pumilio/FBF family of RNA binding proteins in mice, Pumilio 1 (Pum1), is a maternal effect gene. The absence of maternal PUM1 in the oocyte does not affect meiotic maturation but leads to abnormal preimplantation development. Furthermore, genome-wide transcriptome analysis of oocytes and embryos revealed that there is a concomitant perturbation of the mRNA milieu. Of note, putative PUM1 mRNA targets were equally perturbed as non-direct targets, which indicates that PUM1 regulates the stability of maternal mRNAs both directly and indirectly. We show Cdk1 mRNA, a known PUM1 target essential for meiosis and preimplantation development, is not degraded appropriately during meiosis, leading to an increase in CDK1 protein in mature oocytes, which indicates
We investigated the effect mouse cumulus cells (mCCs) on the in vitro maturation (IVM) and developmental potential of bovine denuded germinal vesicle oocytes (DOs). Cumulus-oocyte complexes (COCs), DOs and DOs cocultured with either mCCs (DOs + mCCs) or bovine cumulus cells (bCCs; DOs + bCCs) were subjected to IVM. The meiosis II (MII) rates of DOs, glutathione (GSH) contents, zona pellucida (ZP) hardening and parthenogenetic blastocyst rates of MII oocytes were determined. The relative expression levels of bone morphogenetic protein 15 (BMP-15) and growth differentiation factor 9 (GDF-9) in MII oocytes were measured using quantitative real-time polymerase chain reaction (PCR). mCCs significantly increased the MII rate of DOs from 53.5 ± 3.58% to 69.67 ± 4.72% (p , 0.05) but had no effect on the GSH content (2.17 ± 0.31 pmol/oocyte with mCCs, 2.14 ± 0.53 pmol/oocyte without mCCs). For the DOs + mCCs group, the BMP-15 and GDF-9 expression levels were significantly higher and the ZP ...
Reconstitution of female germ cell development in vitro is a key challenge in reproductive biology and medicine. We show here that female (XX) embryonic stem cells and induced pluripotent stem cells in mice are induced into primordial germ cell-like cells (PGCLCs), which, when aggregated with female gonadal somatic cells as reconstituted ovaries, undergo X-reactivation, imprint erasure, and cyst formation, and exhibit meiotic potential. Upon transplantation under mouse ovarian bursa, PGCLCs in the reconstituted ovaries mature into germinal vesicle-stage oocytes, which then contribute to fertile offspring after in vitro maturation and fertilization. Our culture system serves as a robust foundation for the investigation of key properties of female germ cells, including the acquisition of totipotency, and for the reconstitution of whole female germ cell development in vitro. ...
OBJECTIVE To evaluate the effect of vitrification of mouse oocytes on the behavior of adult offspring. STUDY DESIGN Oocytes from mice were vitrified, warmed and inseminated, and two-cell embryos were transferred to foster mothers. The behavioral characterization of the offspring was detected by the Morris water maze test, forced swimming test, and elevated plus maze test, and compared to that of offspring from fresh oocytes. RESULTS Offspring produced by vitrified oocytes showed normal motor function. In the Morris water maze test of spatial learning there was a slightly decreased time spent in the quadrant containing the platform relative to mice from fresh oocytes, but the difference did not reach statistical significance. In addition, offspring from vitrified oocytes did not exhibit alterations in emotional behavior. CONCLUSION No alterations were found in the behavioral characterization of adult offspring from vitrified oocytes compared with those from fresh oocytes.
Embryo competence depends on oocyte quality, which is affected by different factors, including the treatment modality [12, 13]. We do not know the exact effect of the dosages and types of drugs on oocytes in IVF. Therefore, it was suggested that mild stimulation protocols and natural cycles would reduce aneuploidy rates and increase embryo quality [12]. However, every step during ovulation induction could affect the oocytes and subsequent embryo development.. Triggering oocyte maturation is the last important step of ovulation induction. For a long time, hCG has been used as a triggering agent because of its homology with LH and extended half-life. Although the extended half-life of this molecule might be advantageous for luteal support, its effect on oocyte maturation is not clear and hCG-mediated LH activity differs from natural cycles. Recently, GnRH agonists have been used as the triggering agent, especially in patients at a high risk of OHSS in GnRH antagonist cycles. The GnRHa displaces ...
In somatic cell nuclear transfer in mammals, to clone a piglet is still a big challenge. Although many factors could contribute to the low success rate, such as quality of donor and recipient cells, types of donor cell including sources of animal breeds and tissues, number of passages and culture conditions, timing of cell cycle, procedures of nuclear transfer, techniques and embryos transfer, one of the factors is believed to be poor oocyte activation, especially in pig nuclear transfer. Therefore studies presented in this thesis aimed at the establishment of an in vitro culture system for pig oocyte maturation and embryo culture, based on this system an electrical activation protocol for pig oocytes was optimized and also tested by monitoring in vivo development of activated pig oocytes. Finally, the protocol was used for activating pig embryos reconstructed by transfer of somatic cells into enucleated ovulated oocytes and for production of pig parthenotes to maintain pregnancies of cloned pig ...
TY - JOUR. T1 - Effect of glucose and pyruvate on nuclear and cytoplasmic maturation of porcine oocytes in a chemically defined medium. AU - Funahashi, H.. AU - Koike, T.. AU - Sakai, R.. PY - 2008/10/15. Y1 - 2008/10/15. N2 - The objective was to examine potential roles of glucose and pyruvate in nuclear and cytoplasmic maturation of porcine oocytes. Oocyte-cumulus complexes (OCC), derived from 3 to 6 mm follicles, were cultured in a chemically defined medium (pyruvate-free mNCSU37-PVA), with or without 5.55 mM glucose, during in vitro maturation (IVM); in the absence of glucose, germinal vesicle breakdown (GVBD) and nuclear maturation were prevented (P , 0.05). Subsequently, OCC were cultured for IVM in glucose-containing mNCSU37-PVA supplemented with 6-amononicotinamide (6-AN) and diphenyleneiodonium (DPI), inhibitors of the pentose phosphate pathway (PPP); both compounds (≥10 μM 6-AN and ≥10 nM DPI) inhibited resumption of meiosis (P , 0.05). Supplementation of glucose-free maturation ...
These systems are designed for two-electrode, whole-cell voltage clamping of large cells such as Xenopus oocytes and cell structures such as squid axons. They are either bundled with an Oocyte Clamp Amplifier or a more comprehensive Two Electrode Voltage Clamp Workstation, which provide clamping and amplification of measured signals from glass microelectrodes/sharp electrodes.
In this work, we report an efficient method to easily study transmitter receptors originally assembled in cultured cell lines and then microtransplanted to a sturdy and convenient host cell system, the Xenopus oocyte. This method has been recently used to transplant assembled transmitter receptors from human brain to Xenopus oocyte (7), following a method developed a few years ago to microtransplant AcChoRs and chloride channels from the electric organ of Torpedo to the Xenopus oocyte membrane (5, 6). Here, we injected membrane vesicles prepared from cultured cell lines, and this approach led to a rapid incorporation of neurotransmitter receptors in the oocyte plasma membrane. In this way, functional AMPA-type GluR1, α7-AcChoRs, and α4β2-AcChoRs from cultured cells were microtransplanted to the oocytes, and their respective transmitter-activated currents were analyzed.. We report here that the gross electrophysiological and pharmacological characteristics of the transmitter-gated receptors ...
Guanyl nucleotide binding-proteins, or G-proteins, are ubiquitous molecules that are involved in cellular signal transduction mechanisms. Because a role has been established for cAMP in meiosis and G-proteins participate in cAMP-generating systems by stimulating or inhibiting adenylate cyclase, the present study was conducted to examine the possible involvement of G-proteins in the resumption of meiotic maturation. Cumulus cell-free mouse oocytes (denuded oocytes) were maintained in meiotic arrest in a transient and dose-dependent manner when microinjected with the nonhydrolyzable GTP analog, GTP gamma S. This effect was specific for GTP gamma S, because GppNHp, GTP, and ATP gamma S were without effect. Three compounds, known to interact with G-proteins, were tested for their ability to modulate meiotic maturation: pertussis toxin, cholera toxin, and aluminum fluoride (AlF4-). Pertussis toxin had little effect on maturation in either cumulus cell-enclosed oocytes or denuded oocytes when
Actin assembly is regulated by capping protein, which binds the barbed ends of actin filaments and terminates their elongation. This process is involved in the asymmetric division of mouse oocytes, but the role of capping protein itself is poorly understood. In this study (p. 160), Suk Namgoong, Nam-Hyung Kim and colleagues investigate the roles of capping protein at different stages of mouse oocyte maturation. The authors first show that capping protein mainly localises to the oocyte cytoplasm during maturation. Knockdown of capping protein impaired the asymmetric division of oocytes and increased the polar body size, suggesting that this protein is involved in spindle migration during oocyte migration. In addition, the authors observed a reduction in the cytoplasmic actin mesh in the absence of capping protein. Ectopic overexpression of capping protein also impaired asymmetric division and caused severe abnormalities in polar body extrusion. Time-lapse microscopy confirmed that knockdown or ...
This is the stage of a mature oocyte that has the potential of being fertilized. The stage of metaphase II (MII) indicates that the first meiotic division has been completed and cell cycle is suspended at the MII stage. The pairs of homologue chromosomes are divided in the two resulting cells, which are uneven in size. The larger cell is the oocytes, and the smaller cell is the 1st polar body that has half the number of chromosomes and little cytoplasm.. Immature oocytes cannot be fertilized because they have 46 chromosomes (diploid) hence fertilization by a haploid sperm would give rise to a zygote with 69 chromosomes. However, in some cases immature oocytes can be matured in vitro in the laboratory. During IVF, only a small percentage of oocytes is usually immature.. There is a correlation of oocyte maturation and follicle diameter, although this is not always true. It is possible to collect mature oocytes from smaller follicles and vice versa.. ...
This is the stage of a mature oocyte that has the potential of being fertilized. The stage of metaphase II (MII) indicates that the first meiotic division has been completed and cell cycle is suspended at the MII stage. The pairs of homologue chromosomes are divided in the two resulting cells, which are uneven in size. The larger cell is the oocytes, and the smaller cell is the 1st polar body that has half the number of chromosomes and little cytoplasm.. Immature oocytes cannot be fertilized because they have 46 chromosomes (diploid) hence fertilization by a haploid sperm would give rise to a zygote with 69 chromosomes. However, in some cases immature oocytes can be matured in vitro in the laboratory. During IVF, only a small percentage of oocytes is usually immature.. There is a correlation of oocyte maturation and follicle diameter, although this is not always true. It is possible to collect mature oocytes from smaller follicles and vice versa.. ...
PURPOSE: This project was to determine whether oocytes isolated from virgin aged mice, up to 18 months old, are competent to undergo cytoplasmic maturation in vitro and undergo fertilization and embryonic development. If so, oocyte maturation in vitro could be used as a strategy to rescue valuable genetic resources. RESULTS: Although the number of oocytes recovered from mice was greatly reduced with increasing age, the percentage of oocytes that underwent fertilization, cleavage, and development to the blastocyst stage was essentially unchanged up to 18 months of age. The success of cleavage to the two-cell stage was greater after maturation in vitro (81%) than gonadotropin-induced maturation in vivo (55%). About 20% (20/106) of the embryos derived from oocytes isolated from 18-month-old mice developed to term after embryo transfer. CONCLUSION: Oocytes from virgin aged mice undergo normal cytoplasmic maturation in vitro. Higher percentages of oocytes from aged mice cleave to the two-cell
Protein kinase A (PKA) play a critical role in maintaining the meiotic arrest. However, the steps downstream of PKA remain largely unknown. In this study, we investigated the regulation of meiotic resumption by PKA/Cdc25B pathway in mouse oocytes. Injection of mRNA coding for Cdc25b-S321A had a more potent maturation-inducing ability than Cdc25b-WT. When co-injected with PKA inhibitor, Cdc25B-WT had similar activities with Cdc25B-S321A. Meanwhile, the phosphorylation of Cdc25B-S321 was detected in germinal vesicle (GV) oocytes by Western blotting with a phospho-Ser321-specific antibody and the band disappeared when oocytes reenter into the meiotic cell cycle. Furthermore, Cdc25B-WT translocated to the nucleus shortly before GV breakdown (GVBD), whereas phosphorylated Cdc25B-S321 expressed exclusively in the cytoplasm and the signal could not be detected in GVBD oocytes. Taken together, these data indicate that Cdc25B-Serine321 is the potential PKA target and Cdc25B subcellular localization determines
Infertility is "a disease" that affects the reproductive apparatus making it unable to carry out a successful clinical pregnancy after at least one year of regular and unprotected intercourse [1]. The worldwide prevalence of this disease keeps rising and is estimated to 1 out of 6 couples of reproductive age. Consequently, an increase need for assisted reproductive technologies (ART) to help couples achieving their parenthood project has been recorded. It is important to highlight that regardless of the infertility cause, the oocyte quality is recognized as the main cornerstone amongst others of any successful ART treatment [2]. Consequently, numerous studies focused on the criteria allowing an efficient selection of high-quality oocytes, named also competent oocytes, for assisted reproduction procedure using both human and animal models. Such oocyte competence is defined as its ability to properly achieve full maturation at nuclear, cytoplasmic and molecular levels, to achieve successful steps ...
Background & aim: In vitro maturation and fertilization of oocytes play an important role in reproductive biotechnology. The aim of this study is to define the IGF-1 effect on in vitro maturation, fertilization and development of mice immature oocytes to 2-cells in TCM199 medium cultures. Methods: In this study 4 week ...
During mitosis, a spindle checkpoint detects chromosome misalignment and halts the cell cycle progression. In meiosis of female germ cells, however, it is debatable whether such a checkpoint is present. This research employed a unique model in the mouse, mitotic chromosomes transferred to meiotic cytoplasts to investigate whether a meiotic oocytes microtubule apparatus can effectively separate mitotic metaphase chromosomes, and whether a spindle checkpoint exists during its division. The intact germinal vesicle (GV) oocytes, enucleated GV cytoplasts, and enucleated GV cytoplasts at 15 h in-vitro maturation were transferred with a metaphase fibroblast cell. When mitotic chromosomes were transferred into enucleated or intact mouse GV oocytes, the first bipolar meiotic spindles were established and the reconstructed oocytes were able to extrude polar bodies. However, none of the reconstructed oocytes showed complete and accurate alignment of chromosomes, except the enucleated GV cytoplasts reconstructed
I am a developmental/reproductive biologist studying the development of mammalian oocytes, the cells that become eggs. The focus of my research is on the complex interactions between developing oocytes and their companion follicular somatic cells, the granulosa cells. I found that oocytes are not simply passive recipients of nutrients and signals from ovarian follicular somatic cells, as once believed, but rather actively promote the functions of somatic cells needed to support oocyte development and regulate meiosis. I originated the concept of an oocyte-granulosa cell regulatory loop in which bi-directional communication between the oocyte and companion granulosa cells is essential for both normal oocyte and follicular development. A major goal of my current research is to define the components of this regulatory loop and their functions. I also achieved the first complete development of mammalian oocytes in vitro. This included in vitro initiation of primordial follicle development, oocyte ...
In most species, the cytoplasm of oocytes in primordial follicles exhibits organelles close to the nucleus or uniformly distributed throughout the cytoplasm (Figure 1A and 1B). In humans, groups of organelles are seen close to the nucleus and are named Balbiani bodies [54]. Balbiani body is a large distinctive collection of organelles asymmetrically located near the nucleus in very young oocytes, consisting of mitochondria and associated endoplasmic reticulum surrounding Golgi elements. Besides being well described in human oocytes, they are also found in oocytes of other species (vertebrates and invertebrates). Although the function of mammalian Balbiani body is unknown, this structure may have a possible role in nucleo-cytoplasmic transfer [55],[56].. In any case, the most abundant organelles found in primordial follicle oocytes are round-shaped mitochondria (Figure 1B) [44], which are known to be an immature form of this organelle and develop to an elongated shape as they become mature [57]. ...
Many young cancer patients are now being given the option to store ovarian cortical biopsies before undergoing potentially damaging chemo or radio-therapy. This tissue mainly contains large numbers of immature primordial follicles. Currently the only option to restore fertility using this tissue is by transplantation which may not be a viable option for all patients. Greater options to realise the potential of this tissue to restore fertility could be achieved by the development of in vitro systems that support oocyte development. The ability to develop human oocytes from the most immature stages of follicles (primordial) through to maturation and fertilisation in vitro would revolutionise fertility preservation practice. This has been achieved in mouse where in vitro grown (IVG) oocytes from primordial follicles have resulted in the production of live offspring. However, developing IVG systems to support complete development of human oocytes has been more difficult because of differences in scale of
✅ Answered - [first polar body] [second polar body] [secondary oocyte] [territory oocyte] are the options of mcq question Smaller cell produced by primary oocytes is called realted topics , Biology, Class 10, Reproduction topics with 0 Attempts, 0 % Average Score, 3 Topic Tagged and 0 People Bookmarked this question which was asked on Oct 30, 2018 09:49
Our aims for RC1-00137 entitled "Human Oocyte Development for Genetic, Pharmacological and Reprogramming Applications" are as follows: Aim 1) Assess and compare the potential of multiple nonfederal hESC lines to contribute to the germ cell lineage. Aim 2) Differentiate hESCs to oocytes. Aim 3) Assay the ability of differentiated germ cells to reprogram a somatic nucleus. In the last funding cycle, we have succeeded in extending our analysis of human embryonic stem cell lines and differentiation of the germ cell lineage (that gives rise ultimately to oocytes or eggs) to 11 lines (initially, we proposed 12 lines in total). We have demonstrated that we can control or regulate germ cell differentiation in vitro to increase numbers of germ cells via external and internal induction, and we have succeeded in differentiating germ cells that enter and progress through meiosis, in multiple lines. We have developed the ability to use transplantation to promote mouse oocyte (egg) differentiation (in ...
Xenopus oocytes are naturally arrested at G2 of meiosis I. Exposure to either insulin/IGF-1 or the steroid hormone progesterone breaks this arrest and induces resumption of the two meiotic division cycles and maturation of the oocyte into a mature, fertilizable egg. This process is termed oocyte maturation. The transition is accompanied by an increase in maturation promoting factor (MPF or Cdc2/cyclin B) which precedes germinal vesicle breakdown (GVBD). Most reports point towards the Mos-MEK1-ERK2 pathway [where ERK is an extracellular signal-related protein kinase, MEK is a MAPK/ERK kinase and Mos is a p42(MAPK) activator] and the polo-like kinase/CDC25 pathway as responsible for the activation of MPF in meiosis, most likely triggered by a decrease in cAMP ...
Xenopus oocytes are naturally arrested at G2 of meiosis I. Exposure to either insulin/IGF-1 or the steroid hormone progesterone breaks this arrest and induces resumption of the two meiotic division cycles and maturation of the oocyte into a mature, fertilizable egg. This process is termed oocyte maturation. The transition is accompanied by an increase in maturation promoting factor (MPF or Cdc2/cyclin B) which precedes germinal vesicle breakdown (GVBD). Most reports point towards the Mos-MEK1-ERK2 pathway [where ERK is an extracellular signal-related protein kinase, MEK is a MAPK/ERK kinase and Mos is a p42(MAPK) activator] and the polo-like kinase/CDC25 pathway as responsible for the activation of MPF in meiosis, most likely triggered by a decrease in cAMP ...
The role of Raf and MAPK (mitogen-activated protein kinase) during the maturation of Xenopus oocytes was investigated. Treatment of oocytes with progesterone resulted in a shift in the electrophoretic mobility of Raf at the onset of germinal vesicle breakdown (GVBD), which was coincident with the activation of MAPK. Expression of a kinase-defective mutant of the human Raf-1 protein (KD-RAF) inhibited progesterone-mediated MAPK activation. MAPK activation was also inhibited by KD-Raf in oocytes expressing signal transducers of the receptor tyrosine kinase (RTK) pathway, including an activated tyrosine kinase (Tpr-Met), a receptor tyrosine kinase (EGFr), and Ha-RasV12. KD-RAF completely inhibited GVBD induced by the RTK pathway. In contrast, KD-RAF did not inhibit GVBD and the progression to Meiosis II in progesterone-treated oocytes. Injection of Mos-specific antisense oligodeoxyribonucleotides inhibited MAPK activation in response to progesterone and Tpr-Met, but failed to inhibit these events ...
Phorbol ester (PMA) in concentration 5 and 10ng ml−1 blocks cytokinesis of the second maturation division in mouse oocytes. Karyokinesis is not impaired and digynic triploid oocytes are obtained which undergo first cleavage division.. Effectiveness of blocking cytokinesis is dependent on the timing of exposure of oocytes to PMA action. When oocytes are subjected to PMA at the onset of the second maturation division only 14·5% of eggs are triploid. PMA present during fertilization in vitro (about 1 h exposure to PMA) induces triploidy in 40% eggs. Extending the time of exposure of oocytes to 2 h produces 76% tripronucleate eggs.. Applicability of PMA is compared with the use of cytochalasin B to induce triploidy in the mouse.. ...
TY - JOUR. T1 - Molecular mechanisms responsible for increased vulnerability of the ageing oocyte to oxidative damage. AU - Mihalas, Bettina P.. AU - Redgrove, Kate A.. AU - McLaughlin, Eileen A.. AU - Nixon, Brett. PY - 2017/10/18. Y1 - 2017/10/18. N2 - In their midthirties, women experience a decline in fertility, coupled to a pronounced increase in the risk of aneuploidy, miscarriage, and birth defects. Although the aetiology of such pathologies are complex, a causative relationship between the age-related decline in oocyte quality and oxidative stress (OS) is now well established. What remains less certain are the molecular mechanisms governing the increased vulnerability of the aged oocyte to oxidative damage. In this review, we explore the reduced capacity of the ageing oocyte to mitigate macromolecular damage arising from oxidative insults and highlight the dramatic consequences for oocyte quality and female fertility. Indeed, while oocytes are typically endowed with a comprehensive suite ...
We performed in vitro maturation (IVM) and in vitro fertilization (IVF) of the d3 PGCLC- and PGC-derived oocytes and the WT oocytes at 3 weeks (fig. S6B). Despite differences in COC stability and shape, the PGCLC-derived oocytes reached metaphase II (MII), were fertilized, and developed into two-cell embryos with an efficiency comparable to that of oocytes from other sources (Fig. 2B, fig. S6C, and Table 1). Some of the two-cell embryos from the PGCLCs developed further into blastocysts in vitro [19 of 46 (19/46), ~39%] (Fig. 2B). We transferred the two-cell embryos from PGCLCs, as well as those from the other sources, to separate foster mothers. We obtained newborn pups from the two-cell embryos derived from PGCLCs (5/127, ~3.9%), as well as from those derived from E12.5 PGCs (13/75, ~17.3%) and WT 3-week oocytes (7/55, ~12.7%) (Fig. 2C, fig. S7A, and Table 1). All of these offspring grew similarly into adulthood (fig. S7C). The PGCLC-derived offspring bore the BVSC transgenes, a normal ...
We have previously shown that fatty acid oxidation (FAO) is required for AMP-activated protein kinase (PRKA)-induced maturation in vitro. In the present study, we have further investigated the role of this metabolic pathway in hormone-induced meiotic maturation. Incorporating an assay with 3H-palmitic acid as the substrate, we first examined the effect of PRKA activators on FAO levels. There was a significant stimulation of FAO in cumulus cell-enclosed oocytes (CEO) treated with 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) and RSVA405. In denuded oocytes (DO), AICAR stimulated FAO only in the presence of carnitine, the molecule that facilitates fatty acyl CoA entry into the mitochondria. The carnitine palmitoyltransferase 1 activator C75 successfully stimulated FAO in CEO. All three of these activators trigger germinal vesicle breakdown. Meiotic resumption induced by follicle-stimulating hormone (FSH) or amphiregulin was completely inhibited by the FAO inhibitors etomoxir, mercaptoacetate, and
Oocyte development and maturity classification of boarfish (Capros aper) in the Northeast Atlantic. - ICES Journal of Marine Science, 69: 498-507. This study presents the first detailed investigation of the oocyte development and maturity classification of boarfish, Capros aper, which has recently become the target of an industrial fishery in the Northeast Atlantic. A total of 2014 boarfish were collected from January to December 2010. Mature male and female boarfish were sexually dimorphic and could be readily identified based on external characteristics. A comprehensive maturity scale was developed, which indicated that the length at 50% maturity for males and females was 9.7 cm total length. Female boarfish were observed to spawn in Irish waters in June and July. Once spawning ceased the remaining mature oocytes were resorbed. Preliminary analysis of reproductive strategy indicates that the boarfish is likely an asynchronous batch spawner with indeterminate fecundity ...
Maternal transcripts are accumulated during oocyte growth and drive early embryonic development; therefore, their characterisation is a relevant factor for predicting fertility. DNA microarrays have been the method of choice for transcriptional profiling, but this method has some limitations when applied to domestic species because it relies upon existing knowledge about genome sequence and offers a limited quantitative evaluation. These limits are overcome by next-generation sequencing technology. The aim of the work was to define a reference standard for bovine fertility determining the list and the level of transcripts stored in fully grown oocytes collected from heifers (H) and to compare this pattern with that of adult repeat breeders (RB). Oocytes were collected by ovum pick-up (OPU) from 5 Italian Dappled Red heifers of 11 to 15 months of age that became pregnant at the following oestrus and from 4 adult cows of the same breed with an age of 4 to 7 years, classified as repeat breeders ...
To examine the role of primary amino acid sequence in the localization of proteins within the nucleus, we studied the nucleolar protein NO38 of amphibian oocytes. We synthesized NO38 transcripts in vitro, injected them into the oocyte cytoplasm, and followed the distribution of the translation products. The injected RNA contained a short sequence encoding an epitope derived from the human c-myc protein. We used an mAb against this epitope to detect translation products from injected RNAs by Western blots and by immunofluoresent staining of cytological preparations. When full-length transcripts of NO38 were injected into oocytes, the translation products accumulated efficiently in the germinal vesicle, and a major fraction was localized in the multiple nucleoli. To identify protein domains involved in this nucleolus-specific accumulation, we prepared a series of carboxy-terminal deletions of the cDNA. Oocytes injected with RNA encoding truncated forms of NO38 were examined for altered patterns of ...
It has become a current social trend for women to delay childbearing. However, the quality of oocytes from older females is compromised and the pregnancy rate of older women is lower. With the increased rate of delayed childbearing, it is becoming more and more crucial to understand the mechanisms underlying the compromised quality of oocytes from older women, including mitochondrial dysfunctions, aneuploidy and epigenetic changes. Establishing proper epigenetic modifications during oogenesis and early embryo development is an important aspect in reproduction. The reprogramming process may be influenced by external and internal factors that result in improper epigenetic changes in germ cells. Furthermore, germ cell epigenetic changes might be inherited by the next generations. In this review, we briefly summarise the effects of ageing on oocyte quality. We focus on discussing the relationship between ageing and epigenetic modifications, highlighting the epigenetic changes in oocytes from ...
Figure 1. (Left) Meiotic spindle view of mature oocyte under the Oosight Imaging System; (a) meiotic spindle, (b) first polar body. (Right) The enucleated oocyte and karyoplast containing the meiotic spindle in the pipette; (a) pipette.. 11.Using gentle pressure, inject a single donor cell into the oocyte perivitelline space in HEPES drops on the glass-bottom dish. Perform the injection under the inverted microscope to make sure that a single cell is injected. Fuse the donor cell with the oocyte complex in mannitol fusion medium by applying two consecutive electrofusion pulses of 1.8 V/cm of 15-μsec duration, using an electro-cell manipulator.. 12.Incubate nuclear-transferred oocytes in cleavage medium for 2 h at 37°C in a humidified incubator.. 13.Check the fusion rate under the stereomicroscope by confirming the absence of the donor cell in the perivitelline space.. Check the fusion rate 30 min after fusion. If the donor cell is not fused with the oocyte, repeat the fusion protocol described ...
This work is the first description of the expression of human BCRP in X. laevis oocytes and demonstrates that this heterologous expression system is a valid model for examining the physical and functional characteristics of this ABC half transporter. X. laevis oocytes injected with BCRP cRNA synthesize a protein with the molecular mass of glycosylated BCRP and the immunological characteristics of native human BCRP protein. Our results further demonstrate that oocytes injected with mutant R482T or wild-type BCRP cRNA express BCRP in the oocyte plasma membrane, as evidenced by confocal immunofluorescence microscopic analysis. Accumulation and efflux assays using various BCRP substrate molecules indicate that the oocyte-expressed BCRP functions in a manner analogous to that observed in mammalian systems. Moreover, the X. laevis model indicates that a mutation of serine at codon 187 in the ABC-signature motif of BCRP is not only devoid of transporter activity but also serves in a manner analogous to ...
Many biological phenomena proceed as a result of the accurately timed translation of genetic information into proteins. In the process of oocyte maturation in particular, the timing of protein synthesis is regulated to within a few minutes, and this accurate regulation is what enables the formation of healthy eggs capable of being fertilized by sperm.. This study elucidated that the mRNA accumulated in immature vertebrate oocytes forms granules, and that these granules act as molecular timers in the oocyte to regulate the exact timing of protein synthesis. These findings not only constitute the discovery of a new mechanism for the accurate translation of genetic information into proteins, but may also contribute to progress in the elucidation of the causes of infertility and the development of treatments, as well as explaining the roles of RNA granules in many other different types of cells, including early embryos and neural tissue.. ...
Meiosis in mammalian oocytes pauses in prophase until luteinizing hormone (LH) releases this arrest. One suggestion is that LH does this by closing the gap junctions between the somatic cells that surround the oocyte, thus blocking the transmission of a meiosis-inhibitory signal to oocytes. Now, Norris and co-workers show that LH-induced MAP kinase-dependent gap junction phosphorylation and closure is one of two paths to meiotic resumption in mouse ovarian follicles (see p. 3229). By monitoring the diffusion of fluorescent tracers in intact follicles, the researchers show for the first time that LH decreases the permeability of connexin 43-containing gap junctions between the somatic cells before nuclear envelope breakdown (NEBD; the start of the prophase-metaphase transition) occurs in oocytes. MAP kinase-dependent phosphorylation of connexin 43 causes this decreased permeability, they report. However, surprisingly, inhibition of MAP kinase activation does not prevent NEBD. Thus, they suggest, ...
Poly(A)+ messenger RNA (mRNA) extracted from rat brains or from cat muscles was injected into Xenopus laevis oocytes. This led to the incorporation of voltage-operated Na+ and K+ channels into the oocyte membrane. These channels are not normally present in the oocyte and presumably result from the synthesis and processing of proteins coded by the injected mRNA. Tetrodotoxin blocked the Na+ channels induced by mRNA derived from either innervated or denervated muscle. ...
The in vitro culture environment of cattle embryos can compromise the survival of developing embryos resulting in cell apoptosis. Detection of cell apoptosis is important for determining embryonic quality and reducing embryonic mortality in female animals prior to transfer. In this study the role of cell apoptosis on in vitro embryos was studied, with the focus on oocyte maturation and embryo production, caspase-3 activity and DNA fragmentation. Cow ovaries were collected from local abattoir and a total of 900 COCs were retrieved per week for the study over five-month period (six replicate/per experiments). COCs were randomly allocated to four incubation temperatures (39, 41, 42 and 43 ̊C) for polar body extrusion. Based on maturation results, two preferred temperatures (39 and 41 ̊C) were selected for maturation. Oocytes were subjected to normal subsequent embryonic conditions post maturation. Embryos produced from both maturation temperatures were then examined for embryonic development, ...