Filter...

AnatomyOrganismsDiseasesChemicals and DrugsAnalytical, Diagnostic and Therapeutic Techniques and EquipmentPhenomena and ProcessesInformation Science

Select a category...

MeiosisOocytesOogenesisMetaphaseChromosome SegregationSpindle ApparatusChromosomes, MammalianCyclin B1NocodazoleChromosomesMice, Inbred ICRMicrotubulesOocyte DonationChromosome PairingXenopus laevisMeiotic Prophase IOocyte RetrievalSpermatocytesProphaseSynaptonemal ComplexSpores, FungalXenopusIn Vitro Oocyte Maturation TechniquesFertilizationOvumNondisjunction, GeneticParthenogenesisCrossing Over, GeneticMicroinjectionsOvarySpermatogenesisChromatidsCumulus CellsSpermatozoaMaturation-Promoting FactorProto-Oncogene Proteins c-mosMitosisPachytene StageRecombination, GeneticCentromereCell Cycle ProteinsBlastocystSperm-Ovum InteractionsEmbryonic DevelopmentGerm CellsMolecular Sequence DataSperm Injections, IntracytoplasmicCell NucleusCryopreservationHaploidyPolar BodiesMutationZygoteChromosomes, FungalEmbryo TransferSchizosaccharomyces pombe ProteinsTestisSchizosaccharomycesSaccharomyces cerevisiaeCyclin BAneuploidyCleavage Stage, OvumDiploidyChromosomal Proteins, Non-HistoneSaccharomyces cerevisiae ProteinsCytoplasmAmino Acid SequenceKinetochoresZona PellucidaGametogenesisEmbryo Culture TechniquesSpermatidsRNA, MessengerAnaphasePregnancyCholestenesEgg ProteinsBase SequenceCaenorhabditis elegansXenopus ProteinsNuclear ProteinsOogoniaNuclear Transfer TechniquesGene Expression Regulation, DevelopmentalCDC2 Protein KinaseFollicular FluidCaenorhabditis elegans ProteinsRNA, ComplementaryInfertility, FemaleEmbryo, MammalianOvulation InductionFungal Proteins

MaturationMetaphaseResumptionAneuploidySecondary oocyteMature oocytesOvulationProphaseProgressionProcess called meiosisMiceOogoniaHuman oocytesPrimary oocyteVertebrate oocytesFollicleWoman'sElegans oocytesMammalian meiosisMillion oocytesSegregationUndergoChromosomesEmbryoSpindle assemblyResume meiosisEmbryonicRegulationOvariesMeiotic arrestImmatureSecurinSpermMicrotubulesPolar bodyVitroMouse2022AcentrosomalCauses meiosisOogenesisSeparasePreventsChromosome alignmentReinitiationActinDegradationMRNAsOvaryMembraneOocyte'sMaternalDevelopmentalConsequences

Maturation12

• Many studies show that cumulus expansion is critical for the maturation of the oocyte because the cumulus complex is the oocyte's direct communication with the developing follicle environment. (wikipedia.org)
• During mitosis, cells undergo symmetrical cell division, while oocyte meiotic maturation undergoes two consecutive, asymmetric divisions that generate a totipotent haploid oocyte and two small polar bodies not involved in DNA replication. (bioone.org)
• Ascidians are the closest living relatives of vertebrates, and their study is important for understanding the evolutionary processes of oocyte maturation and ovulation. (elifesciences.org)
• In this study, we first examined the ovulation of Ciona intestinalis Type A by monitoring follicle rupture in vitro, identifying a novel mechanism of neuropeptidergic regulation of oocyte maturation and ovulation. (elifesciences.org)
• CiVP ultimately activated a maturation-promoting factor, leading to oocyte maturation via germinal vesicle breakdown. (elifesciences.org)
• This is the first demonstration of essential pathways regulating oocyte maturation and ovulation in ascidians and will facilitate investigations of the evolutionary process of peptidergic regulation of oocyte maturation and ovulation throughout the phylum Chordata. (elifesciences.org)
• Therefore, the regulatory mechanisms underlying oocyte maturation and ovulation control not only the reproduction of the respective organisms but also evolutionary processes across the animal kingdom. (elifesciences.org)
• Some neuropeptides have been shown to induce oocyte maturation and ovulation (or spawning) in several species of invertebrates. (elifesciences.org)
• These findings demonstrate that various neuropeptides are responsible for triggering oocyte maturation and ovulation in invertebrates, and suggest that oocyte maturation and ovulation and their underlying molecular mechanisms are regulated in both a species-specific and evolutionarily conserved fashion. (elifesciences.org)
• The LH surge promotes maturation of the dominant oocyte, the release of the oocyte and then the luteinization of the granulosa cells and the surrounding theca cells of the dominant follicle resulting in progesterone production. (medscape.com)
• [2] It is developed from the primary oocyte by maturation. (wikipedia.org)
• The main events of human meiosis during egg cell maturation. (scienceinschool.org)

Metaphase4

• The oocyte is arrested in Meiosis II at the stage of metaphase II and is considered a secondary oocyte. (wikipedia.org)
• These disturbances may lead ultimately to errors in chromosome segregation during the metaphase of meiosis, and that faulty segregation to oocyte aneuploidy. (cea.fr)
• Mature oocytes become fertilizable, and their meiosis is arrested again at a species-specific stage: metaphase of the first division (MetI, many invertebrates), metaphase of the second division (MetII, most vertebrates), or G1-phase (some echinoderms and coelenterates) until fertilization. (elifesciences.org)
• [10] Meiosis then proceeds to second metaphase, where it pauses again until fertilization. (wikipedia.org)

Resumption5

• conversely, the resumption of meiosis in response to hormone depends on a decrease in cAMP. (uconn.edu)
• Likewise, injection of an inhibitory antibody made against the α subunit of G s causes meiotic resumption in zebrafish oocytes, as has been reported in Xenopus and mouse oocytes. (uconn.edu)
• Prevents meiosis resumption in prophase-arrested oocytes via CDC25B inactivation by phosphorylation (By similarity). (rcsb.org)
• The midcycle LH surge initiates several physiologic actions including: ovulation, resumption of meiosis in the oocyte, and luteinization. (nih.gov)
• This LH-surge induces the ovulation of the dominant follicle, resumption of oocyte meiosis and subsequently luteinization as indicated by rising progesterone levels. (nih.gov)

Aneuploidy5

• Aneuploidy in mammalian oocytes and the impact of maternal ageing. (uni-goettingen.de)
• Here we show that depletion of Mad2 in meiosis I mouse oocytes induced an increased incidence of aneuploidy. (ncl.ac.uk)
• We conclude that Mad2 delays the onset of cyclin B and securin degradation and averts aneuploidy during meiosis I in mammalian oocytes. (ncl.ac.uk)
• It was the first to be shown to alter oogenesis and lead to the formation of oocytes with an abnormal number of chromosomes (aneuploidy), in turn responsible for numerous miscarriages and fertility disorders. (cea.fr)
• Levasseur MD, Thomas C, Davies OR, Higgins JMG, Madgwick S. Aneuploidy in oocytes is prevented by sustained CDK1 activity through degron masking in cyclin B1 . (ncl.ac.uk)

Secondary oocyte2

• The only normal human type of secondary oocyte has the 23rd (sex) chromosome as 23,X (female-determining), whereas sperm can have 23,X (female-determining) or 23,Y (male-determining). (wikipedia.org)
• This results in the production of a secondary oocyte and one polar body. (wikibooks.org)

Mature oocytes4

• Via genetic and chemical models, the team was able to propose that the deleterious effects of bisphenols on mature oocytes results from their ability to induce oxidative lesions on DNA at a key step in germinal cell differentiation during the fetal period. (cea.fr)
• In a typical IVF procedure, doctors collect a woman's eggs (mature oocytes) and a man's sperm and combine them in a laboratory dish to make embryos for implantation. (riken.jp)
• They must inject themselves daily for four weeks with large doses of hormones to encourage their ovaries to produce numerous mature oocytes while simultaneously suppressing the normal menstrual cycle, which would eject the eggs into the fallopian tubes. (discovermagazine.com)
• at the same time, others are learning how to mature oocytes outside the body. (discovermagazine.com)

Ovulation4

• Oogenesis results in the formation of both primary oocytes during fetal period, and of secondary oocytes after it as part of ovulation. (wikipedia.org)
• After puberty, during each menstrual cycle, one or several oocytes resume meiosis and undergo their first meiotic division during ovulation. (wikibooks.org)
• As follicles grow, they acquire receptors for luteinizing hormone, a pituitary hormone that reinitiates meiosis in the oocyte and causes ovulation of a fertilizable egg. (wikipedia.org)
• Meiosis is then halted until ovulation, and most of the potential egg cells die off again. (scienceinschool.org)

Prophase3

• Meiosis in animal oocytes is arrested at prophase of the first division (ProI). (elifesciences.org)
• The oogonia produce primary oocytes that are arrested in prophase I of meiosis from the time of birth until puberty. (wikibooks.org)
• Mammalian oocytes are maintained in meiotic prophase arrest for a very long time-months in mice, years in humans. (wikipedia.org)

Progression6

• This dissertation concerns the role of heterotrimeric G-proteins in regulating oocyte cAMP levels and meiotic progression, as introduced in chapter one. (uconn.edu)
• Which genes safeguard accurate progression through meiosis is largely unclear. (mpg.de)
• The screen generated an unprecedented annotated data set of meiotic progression in 2,241 mammalian oocytes, which allowed us to analyse systematically which defects are linked to abnormal chromosome segregation during meiosis, identifying progression into anaphase with misaligned chromosomes as well as defects in spindle organization as risk factors. (mpg.de)
• Dot1L mediated histone H3 lysine79 methylation is essential to meiosis progression in mouse oocytes. (nel.edu)
• Wang X, Gao W, Ma X, Wang X, Song C, Huang X, Liu H. Dot1L mediated histone H3 lysine79 methylation is essential to meiosis progression in mouse oocytes. (nel.edu)
• Thomas C, Wetherall B, Levasseur MD, Harris RJ, Kerridge ST, Higgins JMG, Davies OR, Madgwick S. A prometaphase mechanism of securin destruction is essential for meiotic progression in mouse oocytes . (ncl.ac.uk)

Process called meiosis3

• Eggs develop from oocytes in a process called meiosis. (mpg.de)
• Egg and sperm develop in a process called meiosis. (uni-goettingen.de)
• Immature sperm cells, known as spermatocytes, can get stuck part way through the chromosomal-sorting process called meiosis. (riken.jp)

Mice4

• Recombinant human CENP-A and CFA were used to induce ACA production in mice, then mouse MI- and MII-stage oocytes were cultured to investigate chromosome alignment and intracellular IgG localization by immunofluorescence assay in order to explore the involvement of ACA in impaired oocyte meiosis. (biomedcentral.com)
• Shugoshin-2 is essential for the completion of meiosis but not for mitotic cell division in mice. (nature.com)
• In its study performed in a mouse model and published in Environmental Pollution , the team showed that fetal exposure to environmental concentrations of BADGE or BPAF caused oocyte defects in mature mice comparable to those provoked by fetal BPA exposure . (cea.fr)
• Birth of mice from meiotically arrested spermatocytes following biparental meiosis in halved oocytes. (riken.jp)

Oogonia4

• During oogenesis, the oogonia become primary oocytes. (wikipedia.org)
• At about 5 months gestation, the ovaries contain approximately six to seven million oogonia, which initiate meiosis. (wikibooks.org)
• Oogonia enter meiosis during embryonic development, becoming oocytes. (wikipedia.org)
• Oogenesis starts with the process of developing primary oocytes, which occurs via the transformation of oogonia into primary oocytes , a process called oocytogenesis . (wikipedia.org)

Human oocytes3

• Meiosis in human oocytes is highly error-prone, and defective eggs are the leading cause of pregnancy loss and several genetic disorders such as Down's syndrome. (mpg.de)
• In addition, we are studying selected aspects of meiosis in human oocytes. (uni-goettingen.de)
• Mechanism of spindle pole organization and instability in human oocytes. (uni-goettingen.de)

Primary oocyte1

• During the primary oocyte stage of oogenesis, the nucleus is called a germinal vesicle. (wikipedia.org)

Vertebrate oocytes2

• Results in chapter three show that the G s family of G-proteins is required to maintain meiotic arrest in vertebrate oocytes. (uconn.edu)
• Gorr IH, Reis A, Boos D, Wuhr M, Madgwick S, Jones KT, Stemmann O. Essential CDK1-inhibitory role for separase during meiosis I in vertebrate oocytes . (ncl.ac.uk)

Follicle6

• The cumulus-oocyte complex contains layers of tightly packed cumulus cells surrounding the oocyte in the Graafian follicle. (wikipedia.org)
• We targeted 774 genes by RNA interference within follicle-enclosed mouse oocytes to block protein expression from an early stage of oocyte development onwards. (mpg.de)
• As levels of progesterone, estradiol, and inhibin decline 2-3 days before menses, the pituitary begins to release higher levels of follicle-stimulating hormone (FSH), which recruits oocytes for the next menstrual cycle. (medscape.com)
• The remaining oocytes that were initially recruited with the lead follicle undergo atresia. (medscape.com)
• Maintenance of meiotic arrest also depends on the presence of a multilayered complex of cells, known as a follicle, that surrounds the oocyte. (wikipedia.org)
• Removal of the oocyte from the follicle causes meiosis to progress in the oocyte. (wikipedia.org)

Woman's2

• On average, 500-1000 oocytes are ovulated during a woman's reproductive lifetime. (wikibooks.org)
• As an egg cell, or oocyte, matures inside a woman's ovary, it undergoes a type of cell division called meiosis, in which the pairs of chromosomes inside it are lined up and fished apart, and half of them are expelled. (scienceinschool.org)

Elegans oocytes1

• One of Wignall's early studies classified the stages of spindle assembly in C. elegans oocytes. (jhunewsletter.com)

Mammalian meiosis2

• Accordingly, endogenous cyclin A is localized to kinetochores throughout meiosis II, but not in anaphase I. Additionally, we found that cyclin B1, but not cyclin A2, inhibits separase in meiosis I. These findings indicate that separase-dependent cohesin removal is differentially regulated by cyclin B1 and A2 in mammalian meiosis. (ox.ac.uk)
• Actin filaments widely involve into multiple cellular processes such as nuclear positioning, germinal vesicle breakdown, spindle migration, chromosome segregation, spindle rotation and polar body extrusion in oocyte mammalian meiosis. (bioone.org)

Million oocytes2

• The ovaries of a newborn baby girl contain about one million oocytes. (wikibooks.org)
• By puberty there are at most only a quarter of a million oocytes left. (discovermagazine.com)

Segregation2

• Cyclin A2 is required for sister chromatid segregation, but not separase control, in mouse oocyte meiosis. (ox.ac.uk)
• Nuclear positioning, germinal vesicle breakdown, spindle migration, spindle rotation, chromosome segregation, and polar body extrusion are the most critical cellular processes during oocyte meiosis I and II, and a growing number of studies primarily using the mouse oocyte model revealed that actin filaments were critical for these processes, especially for spindle migration. (bioone.org)

Undergo1

• Donors must regularly undergo ultrasound and blood tests to monitor their developing oocytes. (discovermagazine.com)

Chromosomes5

• During her postdoctoral fellowship, Wignall began studying meiosis - a type of cell division that produces reproductive cells with half the number of chromosomes - occurring in female reproductive cells or oocytes. (jhunewsletter.com)
• We then analysed the function of several genes simultaneously by high-resolution imaging of chromosomes and microtubules in live oocytes and scored each oocyte quantitatively for 50 phenotypes, generating a comprehensive resource of meiotic gene function. (mpg.de)
• In meiosis, two specialized cell divisions allow the separation of paired chromosomes first, then of sister chromatids. (ox.ac.uk)
• All that fluid cytoplasm sloshing around inside the oocyte seemed to encumber the ability of chromosomes to divvy themselves up properly. (riken.jp)
• The oocyte is a big cell, but the chromosomes sit in only a small part of that cell, and that's what we were interested in. (scienceinschool.org)

Embryo4

• The oocyte, a large and complex cell, must be supplied with numerous molecules that will direct the growth of the embryo and control cellular activities. (wikipedia.org)
• In the present study, we hypothesized that ACA might be the major antibody in the ANA family to have adverse impacts on oocyte and embryo potential. (biomedcentral.com)
• This specialized division allows most maternal components to be maintained in the oocytes for early embryo development. (bioone.org)
• A human female embryo develops around 7 million proto-eggs, known as primordial oocytes. (discovermagazine.com)

Spindle assembly1

• A liquid-like spindle domain promotes acentrosomal spindle assembly in mammalian oocytes. (uni-goettingen.de)

Resume meiosis1

• Injection of RNA encoding a dominant negative form of G s causes Xenopus and mouse oocytes to resume meiosis. (uconn.edu)

Embryonic2

• Thus, oocytes of many organisms are protected from oxidative DNA damage while storing up a large mass of substances to nurture the zygote in its initial embryonic growth. (wikipedia.org)
• The oocyte receives mitochondria from maternal cells, which will go on to control embryonic metabolism and apoptotic events. (wikipedia.org)

Regulation1

• This is a simple visual screen that can be used to identify G-protein coupled receptors, including receptors involved in the regulation of meiosis in oocytes. (uconn.edu)

Ovaries2

• Histology evaluation: Tiny ovaries with no growing oocytes or follicles (see 3). (jax.org)
• When a young woman reaches puberty around age 10 to 13, a promary oocyte is discharged from one of the ovaries every 28 days. (wikibooks.org)

Meiotic arrest2

• However, as the oocyte grows, these proteins are synthesized, and meiotic arrest becomes dependent on cyclic AMP . (wikipedia.org)
• In the oocyte, cyclic GMP prevents the breakdown of cyclic AMP by the phosphodiesterase PDE3, and thus maintains meiotic arrest. (wikipedia.org)

Immature1

• All they did was halve the volume of the immature oocytes. (riken.jp)

Securin1

• Proteolysis of cyclin B and securin commenced earlier in Mad2-depleted oocytes, resulting in a shortened duration of meiosis I. Furthermore, overexpression of Mad2 inhibited homolog disjunction. (ncl.ac.uk)

Sperm1

• This process directs the repair of many DNA lesions in somatic cells and generates genetic variation in sperm and egg cells during meiosis. (cshlpress.com)

Microtubules1

• The partitioning of mitochondria is carried out by a system of microtubules that will localize mitochondria throughout the oocyte. (wikipedia.org)

Polar body1

• The polar body divides in two, the secondary egg cell divides into a third polar body and a mature egg cell, and meiosis is complete. (scienceinschool.org)

Vitro2

• The work in our laboratory combines several innovative approaches towards understanding the fundamental principles underlying meiosis, including advanced microscopy techniques (such as super-resolution, light sheet, expansion, and focused ion beam electron microscopy), loss-of-function approaches (Trim-Away, RNAi in cultured follicles, and mouse genetics), as well as in vitro ovarian culture and sequencing (including single-cell RNA-seq). (uni-goettingen.de)
• In vitro clinic: No oocytes recovered. (jax.org)

Mouse3

• We conducted this study to investigate whether ACA could penetrate into the living oocytes and interfere with oocyte meiosis in a mouse model. (biomedcentral.com)
• Most of our work is carried out in mouse oocytes, which are easily available and can be studied with state-of-the-art molecular biology, genetic and advanced imaging tools. (uni-goettingen.de)
• Moreover, we use bovine and porcine oocytes as model systems for aspects of meiosis that are not well conserved in the mouse. (uni-goettingen.de)

20221

• 2022). Multidrug resistance transporter-1 dysfunction perturbs meiosis and Ca2+ homeostasis in oocytes . (umass.edu)

Acentrosomal3

• Sadie Wignall, a professor at Northwestern University, delves into the secrets of spindle formation in acentrosomal oocytes in her seminar at Hopkins. (jhunewsletter.com)
• The seminar , titled "Stabilizing a Dynamic Structure: Mechanisms that Maintain Acentrosomal Spindle Integrity During Oocyte Meiosis," was hosted by the Department of Biology at Hopkins for their seminar series. (jhunewsletter.com)
• Although oocytes in humans and most model organisms exhibit acentrosomal spindles, the Wignall lab chose to use the nematode Caenorhabditis elegans ( C. elegans ) as their main model system because the transparent bodies of C. elegans allow for live imaging of these processes. (jhunewsletter.com)

Causes meiosis1

• This is demonstrated by evidence that activation of exogenously expressed G i -linked 7-transmembrane receptors causes meiosis to resume in starfish oocytes, but not Xenopus oocytes. (uconn.edu)

Oogenesis1

• The formation of an oocyte is called oocytogenesis, which is a part of oogenesis. (wikipedia.org)

Separase2

• Separase removes the cohesin complex holding sister chromatids together in a stepwise manner from chromosome arms in meiosis I, then from the centromere region in meiosis II. (ox.ac.uk)
• namely, its requirement for separase-dependent sister chromatid separation in meiosis II. (ox.ac.uk)

Prevents1

• Untimely cyclin A2-associated kinase activity in meiosis I leads to precocious sister separation, whereas inhibition of cyclin A2 in meiosis II prevents it. (ox.ac.uk)

Chromosome alignment1

• Chromosome alignment and intracellular IgG localization in MI- and MII-stage oocytes were investigated by immunofluorescence analysis. (biomedcentral.com)

Reinitiation1

• Results in chapter two show that the reinitiation of meiosis in oocytes of starfish, but not frog, occurs through activation of the G i family of G-proteins. (uconn.edu)

Actin1

• The present review summarizes recent progress made regarding the roles of actin filaments in the asymmetric oocyte division. (bioone.org)

Degradation1

• CiErk1/2 also induced expression of matrix metalloproteinase (CiMMP2/9/13) in the oocyte, resulting in collagen degradation in the outer follicular cell layer and liberation of fertile oocytes from the ovary. (elifesciences.org)

MRNAs4

• During the growth of the oocyte, a variety of maternally transcribed messenger RNAs, or mRNAs, are supplied by maternal cells. (wikipedia.org)
• These mRNAs can be stored in mRNP (message ribonucleoprotein) complexes and be translated at specific time points, they can be localized within a specific region of the cytoplasm, or they can be homogeneously dispersed within the cytoplasm of the entire oocyte. (wikipedia.org)
• Below are some examples of maternally inherited mRNAs and proteins found in the oocytes of the African clawed frog. (wikipedia.org)
• Mammalian oocytes store mRNAs in a mitochondria-associated membraneless compartment. (uni-goettingen.de)

Ovary1

• An oocyte is produced in a female fetus in the ovary during female gametogenesis. (wikipedia.org)

Membrane3

• These results support the hypothesis that there is a G s -activating receptor in the oocyte membrane that maintains vertebrate oocyte arrest. (uconn.edu)
• [5] The cyclic AMP is generated by the oocyte by adenylyl cyclase in the oocyte membrane. (wikipedia.org)
• The adenylyl cyclase is kept active by a constitutively active G-protein-coupled receptor known as GPR3 and a G-protein, Gs, also present in the oocyte membrane. (wikipedia.org)

Oocyte's2

• If this metabolic activity were carried out by the oocyte's metabolic machinery, the oocyte genome would be exposed to the reactive oxidative by-products generated. (wikipedia.org)
• It was proposed that, in order to avoid damage to the DNA genome of the oocytes, the metabolism contributing to the synthesis of much of the oocyte's constituents was shifted to other maternal cells that then transferred these constituents to oocytes. (wikipedia.org)

Maternal1

• As the oocyte is a product of female gametogenesis, the maternal contribution to the oocyte and consequently the newly fertilized egg, is enormous. (wikipedia.org)

Developmental1

• Because the fate of an oocyte is to become fertilized and ultimately grow into a fully functioning organism, it must be ready to regulate multiple cellular and developmental processes. (wikipedia.org)

Consequences1

• Their results show that oxidative damage caused by the substitutes has important consequences on oocyte quality. (cea.fr)