An oocyte, ovocyte, or rarely oöcyte is a female gametocyte or germ cell involved in reproduction. The oocyte is produced in the ovary by an ancestral cell called an oogonium and gives rise to the ovum (the egg) which can be fertilized.

Bicaudal-D (Bic-D)

• required for the differentiation of an oocyte and hence for fertility. Phosphorylation of the Bic-D protein is essential for its accumulation in the pro-oocyte and that this process leads to the gradual localization to the pro-oocyte of factors required for oocyte differentiation. PMID: 1959135
• essential for the establishment of oocyte fate and subsequently for polarity formation within the developing Drosophila oocyte. PMID: 10825285

BMP15 (bone morphogenetic protein 15)

• oocyte-specific growth factor that appears to play key roles in granulosa cell development and fertility in most mammalian species. PMID: 15531364
• a member of the transforming growth factor beta (TGFbeta) superfamily and is specifically expressed in oocytes. PMID: 10888873
• has proven to be critical for normal fertility in female mammals. PMID: 15836954
• a novel oocyte-derived growth factor. PMID: 11741284

c-kit

• we found for the first time the presence of c-kit mRNA and soluble c-kit protein in human oocytes and follicular fluid. PMID: 9543148
• ovarian c-kit, found primarily on oocytes, has autophosphorylation activity, and c-kit and KL are required for maintenance of oocyte growth in vitro. PMID: 7507447

c-Mos

• defined as the candidate initiator of Xenopus oocyte maturation. PMID: 11730318
• mos and cdc2, in addition to functioning as key regulators of the meiotic cell cycle, cooperate in the translational activation of a specific maternal mRNA during oocyte maturation. PMID: 10564256
• cap ribose methylation of c-mos mRNA is important for translational recruitment and for the progression of oocytes through meiosis. PMID: 9628920
• essential for the initiation of oocyte maturation, for the suppression of DNA synthesis during meiosis, and for the second metaphase arrest in Xenopus. PMID: 8864742
• a key element in the cascade of events leading to meiotic maturation of vertebrate oocytes. PMID: 7988567

Estradiol

• can be considered as a marker not only of oocyte maturity but also of oocyte quality. PMID: 16021855, PMID: 3678516

GDF9 (growth and differentiation factor 9)

• oocyte-specific growth factor that appears to play key roles in granulosa cell development and fertility in most mammalian species. PMID: 15531364

HBPP (heparin-binding placental protein)

• a marker of in-vivo and in-vitro oocyte activation and embryo quality. PMID: 2254408

IGFBP-1

• a marker for oocyte maturation. PMID: 9359637

Kit Ligand (KL)

• produced in rat granulosa cells at particularly high levels in the cells closest to the oocyte and that this production may be regulated directly by gonadotropic hormones. PMID: 9052937

Leptin

• is the product of the obese gene (ob), and is secreted in plasma from mature adipocytes. It has been recently reported that leptin is synthesized in granulosa and cumulus cells within the follicle of the ovary, and is present in mature human oocytes, suggesting possible roles of leptin in several aspects of pre- and post-ovulatory follicular development. PMID: 10080923

LH Receptor (LH-R)

• a potential marker of oocyte developmental competence and characterization of the bovine splicing isoforms. PMID: 12611607

MATER (maternal antigen that embryos require)

• an oocyte-specific protein essential for early development. The presence of MATER protein in mitochondria and nucleoli suggests that it may participate in both cytoplasmic and nuclear events during early development. PMID: 14670992

MSY2

• a germ-cell-specific member of the Y-box family of DNA-/RNA-binding proteins, is proposed to function as a coactivator of transcription in the nucleus and to stabilize and store maternal and paternal mRNAs in the cytoplasm. PMID: 15824319
• is implicated in regulating the stability and translation of maternal mRNAs during mouse oogenesis. PMID: 15031116
• a mouse germ cell-specific Y-box protein, is implicated in the global regulation of the stability and/or translation of maternal mRNAs in the mouse oocyte. PMID: 12648488
• a mouse germ cell-specific Y-box protein, in oocytes and its degradation by the late two-cell stage suggest that MSY2 may stabilize and/or regulate the translation of maternal mRNAs. PMID: 12297523
• MSY2 expression is highly restricted and essentially confined to the oocyte in the female mouse. PMID: 11566752

NALP9

• a novel oocyte marker gene in cattle. PMID: 15892040

Orb

• localized at the appropriate sites within the oocyte before the arrival of the mRNAs encoding axis determinants. PMID: 11245581

Oskar

• tightly localized at the posterior pole of the oocyte. PMID: 12538512

p180

• p180 synthesis is thus a useful, reliable molecular marker of oocyte maturation. PMID: 1699641

Pentraxin 3

• a possible marker for oocyte quality. PMID: 15831290

Stat-3

• an oocyte marker which stains the cytoplasm of all oocytes, has critical role in early mammalian development, and may be involved in the determination of the animal pole of the oocyte and in the establishment of the inner cell mass and trophoblast in the preimplantation stage embryo. PMID: 9464852

VASA

• a DEAD box mRNA helicase similar to eIF4A, is involved in pole plasm assembly in the Drosophila oocyte and appears to regulate translation of oskar and nanos mRNAs. PMID: 9521910
• required for GURKEN accumulation in the oocyte, and is involved in oocyte differentiation and germline cyst development. PMID: 9521895

ZP (zona pellucida, ZP1, ZP2, ZP3 or ZPA, ZPB, ZPC)

• zona pellucida (ZP) is an extracellular coat synthesized and secreted by the oocyte during follicular development and surrounding the plasma membrane of mammalian eggs. Ovarian oocytes and not granulosa cells are the only source for mouse ZP glycoproteins. PMID: 11906903
• an extracellular glycoprotein coat that is deposited around the oocyte during folliculogenesis and performs several functions that relate to fertilisation and preimplantion development. In eutherian mammals it consists of three major glycoproteins--ZPA, ZPB, and ZPC. PMID: 10533707

ZAR1 (zygotic arrest 1)

• a novel maternal-effect gene critical for the oocyte-to-embryo transition. PMID: 12539046
• one of the few known oocyte-specific maternal-effect genes essential for the beginning of embryo development discovered in mice, expressed exclusively in oocytes in pig ovary, persisted during first cleavages in embryos developed in vivo and declined sharply in morulae and blastocysts. PMID: 16551357

Other Oocyte Markers

• Corona radiata density as a non-invasive marker of bovine cumulus-corona-oocyte complexes selected for in vitro embryo production. PMID: 16727905
• An immunocytochemical technique for analysis of regulation of genes encoding early differentiation marker antigens in an oocyte translation system. PMID: 9138534
• conversion of GDP-mannose into GDP-fucose in Nereids: a biochemical marker of oocyte maturation. PMID: 6208023
• Fluorescent berberine binding as a marker of internal glycosaminoglycans sulfate in bovine oocytes and sperm cells. PMID: 15551746
• Spatio-temporal expression of the germ cell marker genes MATER, ZAR1, GDF9, BMP15,andVASA in adult bovine tissues, oocytes, and preimplantation embryos. PMID: 15189828
• Increased birefringence in the meiotic spindle provides a new marker for the onset of activation in living oocytes. PMID: 10859266
• Serum follicle-stimulating hormone inhibition is a marker for preovulatory oocytes in in-vitro fertilization and embryo transfer. PMID: 2501334
• Metabolic markers of developmental competence for in vitro-matured mouse oocytes. PMID: 16183865
• Comparison of Hoechst 33342 and propidium iodide as fluorescent markers for sperm fusion with hamster oocytes. PMID: 1285064
• Radiolanthanides as markers for vitellogenin-derived proteins in the growing oocytes of the Japanese quail. PMID: 7193323
• In silico identification and structural features of six new genes similar to MATER specifically expressed in the oocyte. PMID: 15474461