Leptin has been shown to exert positive effects during the maturation of bovine oocytes, influencing blastocyst development, apoptosis, and the transcript levels of developmentally important genes. The present study was conducted to characterize further the mechanisms of leptin action on oocytes and the role of cumulus cells (CCs) in this context. In the first series of experiments, cumulus-ooc...

The factor(s) produced by porcine cumulus cells (cumulus cell factor (s): CCF) was described as quantitatively inhibiting the maturation of oocytes in vitro (Petr et al, 1989). When 1, 10, 20 or 40 cumulus oocyte complexes (COCs) were cultured in a droplet of medium (vol 10 microliters), germinal vesicle breakdown (GVBD) was observed in 85, 78, 57 or 19% of the oocytes, respectively. GVBD was o...

The cryopreservation of female gametes is still an open problem because of their structural sensitivity to the cooling-and-freezing process and to the exposure to cryoprotectants. The present work was aimed to study the effect of vitrification on immature bovine oocytes freed of cumulus cell investment before freezing. To verify the feasibility and efficiency of denuded oocyte (DO) cryopreserva...

Few studies demonstrate at a biochemical level the metabolic profile of both cumulus cells and the oocyte during maturation. The aim of the present study was to investigate the differential participation of enzymatic activity in cumulus cells and in the oocyte during in vitro maturation (IVM) by studying the activity of enzymes involved in the control of amino acid metabolism, alanine aminotran...

Cumulus-oocyte complexes were aspirated from small antral follicles (3-5 mm in diameter) and divided into 2 groups: complexes in which a dark rim of corona cells were visible around the zona pellucida (group 1); and those in which the corona displayed the same density as the rest of the cumulus cell mass (group 2). Cumulus complexes of both groups were evaluated by acetoorcein staining, scannin...

CONTEXT FSH is routinely administered to in vitro fertilization patients to induce follicle maturation. During this process, granulosa cells differentiate and acquire specific functional characteristics that are required to coordinate ovulation and oocyte maturation. OBJECTIVE The objective of the study was to gain insight into the molecular mechanisms regulating human granulosa cell differen...

Retinoids, a class of compounds that include retinol and its metabolite, retinoic acid, are absolutely essential for ovarian steroid production, oocyte maturation, and early embryogenesis. Previous studies have detected high concentrations of retinol in bovine large follicles. Further, administration of retinol in vivo and supplementation of retinoic acid during in vitro maturation results in e...

A search for genes expressed more highly in mouse cumulus cells than mural granulosa cells by subtraction hybridization yielded Slc38a3. SLC38A3 is a sodium-coupled neutral amino acid transporter having substrate preference for l-glutamate, l-histidine, and l-alanine. Detectable levels of Slc38a3 mRNA were found by in situ hybridization in granulosa cells of large preantral follicles, but level...