In the brachiopod Terebratalia transversa, each ovarian follicle consists of (i) a prophase-arrested oocyte with an enlarged nucleus (= the germinal vesicle, or GV), and (ii) a surrounding sheath of follicle cells that attach to the oocyte by means of junctional complexes. Within about 80 min after removing a follicle from the ovary, the follicular sheath undergoes a microfilament-mediated retr...

1. Methylxanthines (IBMX, caffeine, theophylline), which are known inhibitors of c-AMP phosphodiesterase inhibited reversibly progesterone-induced maturation of Xenopus oocyte. 2. The time course of protein phosphorylation during maturation stimulated by progesterone was analysed in Xenopus oocyte : protein phosphorylation increased around germinal vesicle breakdown (GVBD). No quantitative chan...

BACKGROUND Activin and inhibin are glycoproteins structurally related to the transforming growth factor-beta superfamily. These peptides were first described as factors that regulate the follicle-stimulating hormone (FSH) at the pituitary level. The possible role of inhibin and activin, at the ovarian level, in mediating the stimulatory actions of a Fundulus pituitary extract (FPE) and 17alpha,...

Calcineurin (CN) is a serine/threonine phosphatase which plays important roles in meiosis maturation in invertebrate oocytes; however, the role of CN in mouse oocytes is relatively unexplored. In this study, we examined the expression, localization and functional roles of CN in mouse oocytes and granulosa cells. The RT-PCR results showed that the β isoform of calcineurin A subunit (Cn A) expres...

For successful fertilization by the male gamete, oocyte cytoplasmic organelles such as the Golgi apparatus have to undergo specific changes: the entire process is known as cytoplasmic maturation. The goal of this study was to unravel the dynamics of the Golgi apparatus in bovine oocytes at critical stages of in vitro maturation, i.e. germinal vesicle (GV), GV breakdown (GVBD), metaphase I (MI) ...

Taxol, a drug which promotes microtubule assembly, was used to assess the microtubule nucleating activity of pericentriolar material (PCM) in mouse oocytes prevented from undergoing germinal vesicle breakdown (GVBD), compared with oocytes allowed to proceed normally through GVBD and also in nucleate and anucleate oocyte fragments. Both immunofluorescence staining and ultrastructural analysis re...

The tyrosine phosphorylation/dephosphorylation of p34 was estimated by immunoblotting with antiphosphotyrosine antibody during meiotic maturation of Xenopus oocytes. At the time of germinal vesicle breakdown (GVBD), p34 is tyrosine dephosphorylated whereas a p42 protein, which might correspond to a MAP2 kinase, becomes tyrosine phosphorylated. No modification in the level of tyrosine phosphoryl...

Two studies were conducted with the overarching goal of determining the extent to which lipolytic changes relate to germinal vesicle breakdown (GVBD) in bovine oocytes matured under thermoneutral or hyperthermic conditions. To this end, cumulus-oocyte complexes underwent in vitro maturation for 0, 2, 4, 6 or 24 h at 38.5 (first study) or 38.5 and 41.0 C (second study; heat stress applied up thr...

The maturation hormone 1-methyladenine (1-MA) causes meiotic resumption of prophase arrested immature starfish oocytes. Continuous exposure to > or = 0.5 microM 1-MA causes germinal vesicle breakdown (GVBD) in approximately 20 min, but oocytes pretreated for > 30 min with a subthreshold dose of 1-MA undergo GVBD much faster (approximately 10 min) when they are exposed to 1 microM 1-MA. Furtherm...

ZP3 is a principal component of the zona pellucida (ZP) of mammalian oocytes and is essential for normal fertility, and knockout of ZP3 causes complete infertility. ZP3 promotes fertilization by recognizing sperm binding and activating the acrosome reaction; however, additional cellular roles for ZP3 in mammalian oocytes have not been yet reported. In the current study, we found that ZP3 was st...