In mammalian females, germ cells remain arrested as primordial follicles. Resumption of meiosis is heralded by germinal vesicle breakdown, condensation of chromosomes, and their eventual alignment on metaphase plates. At the first meiotic division, anaphase-promoting complex/cyclosome associated with Cdc20 (APC/CCdc20) activates separase and thereby destroys cohesion along chromosome arms. Beca...

Calcium handling is critical for the oocyte function, since the first steps of fertilization are dependent on the appropriate Ca(2+) mobilization to originate transient spikes of the cytosolic Ca(2+) concentration. It is well known that the Ca(2+) influx from the extracellular milieu is required to maintain this signaling in mammalian oocytes. However, the regulation of the Ca(2+) channels invo...

Background An evaluation of the developmental competence of vitrified mouse germinal vesicle (GV) oocytes with various equilibration and vitrification times; in the presence or absence of cumulus cells and by comparison between the cryotop method and straws was performed. MaterialsAndMethods Mouse GV oocytes were considered in cumulus-denuded oocytes (CDOs) and cumulus-oocyte complexes (COCs) g...

The oocyte's meiotic spindle is a dynamic structure that relies on microtubule organization and regulation by centrosomes. Disorganization of centrosomal proteins, including the nuclear mitotic apparatus (NuMA) protein and the molecular motor complex dynein/dynactin, can lead to chromosomal instability and developmental abnormalities. The present study reports the distribution and function of t...

Background: Oocyte cryopreservation is one of the most important topics in the field of assisted reproductive technology to preserve women fertility, but relationship between cryopreservation and apoptosis is still a matter of debate. The present study was aimed to investigate the effects of vitrification on apoptosis in mouse oocytes by Cryotop method. Method: A total of 200 germinal vesicle (...

We evaluated the ability of immature pig oocytes (at germinal vesicle stage) to detect differences in the in vitro penetration rates of boar spermatozoa. In Experiment 1, immature and ovulated oocytes (n=303) were exposed to capacitated boar spermatozoa to determine if the penetrability of immature pig oocytes was comparable to that of ovulated oocytes. The percentages of penetrated oocytes and...

Ceramide regulates many cellular processes, including cell growth, differentiation, and apoptosis. Although the effects of exogenous bacterial neutral sphingomyelinase (SMase) in Xenopus laevis oocytes have been investigated, its microinjection into oocytes has not been reported previously. Thus, we compared the incubation versus microinjection of the neutral Bacillus cereus sphingomyelinase (b...

Background: The use of C-type natriuretic peptide (CNP) combined with cysteamine during pre-in vitro maturation (IVM) can help establish an effective pre-IVM system. Aims: This study was designed to investigate the effects of CNP combined with cysteamine on meiotic maturation and developmental competence of bovine oocytes in vitro. Met...

Developing a culture system for preantral follicles has important biotechnological implications due to the potential to produce a large number of oocytes for embryo production and transfer. To accomplish this goal, the present study was aimed to culture preantral follicles in the presence of different media, sera and FSH concentrations. Six-week-old preantral follicles (95 ± 5 µm) were cultured...

The arrest of meiotic prophase in mammalian oocytes within fully grown follicles is dependent on cyclic adenosine monophosphate (cAMP) regulation. A large part of cAMP is produced by the Gs-linked G-protein-coupled receptor (GPR) pathway. In the present study, we examined whether GPR3 is involved in the maintenance of meiotic arrest in porcine oocytes. Expression and distribution of GPR3 were e...