a:4:{s:10:"Background";s:206:"The aim of the present study was to investigate the role of progesterone on the developmental competence of cumulus-oocyte complexes (COCs) and cumulus-denuded oocytes (CDOs) at germinal vesicle (GV) stage.";s:19:"MaterialsAndMethods";s:485:"GV oocytes of pregnant mare's serum gonadotropin (PMSG)-primed prepubertal mice were divided into two groups: CDOs and COCs. ...

During the winter season the full grown Bufo arenarum oocyte shows the metabolic behaviour characteristic of differentiated tissues of the same species. Due to seasonal variations, during the amplexus period, it acquires the metabolic behaviour of the segmenting egg. Short-time-induced ovulations (5-6 h) determine germinal vesicle breakdown immediately before the expulsion of the oocyte, withou...

During follicular atresia in the sheep and pig there is a marked reduction in the vasculature of the theca interna underlying the membrana granulosa. In the sheep there is no reduction of thecal blood vessels adjacent to the cumulus which remains viable. By contrast, in the pig the cumulus degenerates during atresia and the underlying thecal vasculature is greatly diminished. However, despite l...

Genes involved in the echinoderm block to polyspermy are synthesized primarily in the oocyte. Their expression begins early in oogenesis and continues until germinal vesicle breakdown, when the transcript is rapidly turned over, leaving only traces of the active transcript. These oocyte-specifi c genes encode proteins in the egg extracellular matrix and the cortical granules, secretory vesicles...

Background: Cryopreservation of oocytes, which is an interesting procedure to conserve female gametes, is an essential part of reproductive biotechnology. The objective of the present study was to investigate the effects of cumulus cells on survival,in vitro maturation,fertilization and subsequent developmental capacity of mouse germinal vesicle stage oocytes during vitrification. Materials and...

Oocyte development is characterized by impressive changes in chromatin structure and function in the germinal vesicle (GV) that are crucial in conferring to the oocyte meiotic and developmental competence. During oogenesis, oocyte and follicular cells communicate by paracrine and junctional mechanisms. In cow, cumulus-enclosed oocytes (CEOs) isolated from early antral follicles have uncondensed...

Using oocytes isolated from juvenile and adult mice, we have examined the qualitative patterns of protein synthesis during growth and during meiotic maturation of these oocytes. Oocytes were cultured in a denned medium in the presence of [^Slmethionine and radioactively labelled proteins were separated by SDS-polyacrylamide gel electrophoresis and detected by fluorography. The results of these ...

Background: The effects of cumulus cells and the effectiveness of a PDE3 specific inhibitor (Cilostamide) in comparison with an adenylate cyclase activator (Forskolin) on the maturation rate and developmental competence of mouse germinal vesicle (GV) oocytes were evaluated Materials and Methods: Germinal vesicles (GV) oocytes of PMSG-primed mice were divided into cumulus denuded oocytes (CDOs) ...

BACKGROUND With improved prospects for the use of human oocyte in-vitro maturation in assisted reproductive technologies, the need to define more clearly the coordination of nuclear and cytoplasmic maturation has arisen. METHODS Immunofluorescence and confocal microscopy were used to evaluate cell cycle-dependent modifications in chromatin and microtubules in human germinal vesicle oocytes (n...