Immature oocytes become fertilisable eggs through a process called meiotic maturation, which is often induced by specific hormones. Oocyte maturation involves the activation of various signal transduction pathways that converge to activate maturation-promoting factor (MPF); this is a key activity that catalyses entry into M-phase of meiosis I and meiosis II. Whereas the function of MPF in promo...

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 6mm 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...

background: routine oocytes cryopreservation remained an elusive technique in the wide ranges of available assisted reproductive technologies. the microtubules of oocytes are vulnerable to cryoprotectants and thermal change during cryopreservation. objective: the effects of a vitrification protocol were investigated on the spindle and chromosome configurations of mice oocytes cryopreserved at t...

Spawning was induced in both male and female Pismo clams by injecting 0.4 ml of 5 mM serotonin into the gonad. Spawned oocytes had already matured to metaphase I of meiosis or were undergoing germinal vesicle breakdown at the time of release. Prophase-arrested oocytes scraped from the ovaries of uninjected clams were induced to undergo germinal vesicle breakdown in vitro by incubating them with...

Polychlorinated biphenyls (PCBs) are endocrine-disrupting chemicals that mimic estrogen in fish. Among the various PCBs, 3,3’,4,4’,5-pentachlorobiphenyl (PCB126), considered an antagonist, has been reported to elicit estrogenic activity We investigated potency of PCB126 vitro oocyte maturation dusky tripletooth goby, Tridentiger obscurus . In this study, we quantified steroid metabolites follow...

Although securin/separase/cohesion pathway was reported to regulate chromosome segregation during meiotic metaphase-to-anaphase transition, little biochemical evidence was provided. We recently found that oocytes could not progress beyond meiotic metaphase when ubiquitin-proteasome pathway was inhibited, but the mechanisms remain unclear. In the present study, we investigated the quantity of se...

BACKGROUND Shortly after stimulation by the preovulatory surge of luteinizing hormone (LH), oocytes arrested at the late prophase I resume meiosis characterized by germinal vesicle breakdown (GVBD), chromosome condensation, and extrusion of the first polar body in preparation for fertilization and early embryonic development. However, oocytes express few or no LH receptors and are insensitive t...