Mammalian oocyte development is characterized by impressive changes in chromatin structure and function within the germinal vesicle (GV). These changes are crucial to confer the oocyte with meiotic and developmental competencies. In cow, oocytes collected from early and middle antral follicles present four patterns of chromatin configuration, from GV0 to GV3, and its progressive condensation ha...

Based on new knowledge coming from marine perciform species, the origin of oocytes and their development in the Ostariophysi, Gymnotus sylvius is described. In both Gymnotus sylvius and marine perciform fish, oogonia are found in the germinal epithelium that forms the surface of the ovarian lamellae. At the commencement of folliculogenesis, proliferation of oogonia and their entrance into meios...

We report on a binuclear human oocyte that underwent maturation in vitro from germinal vesicle stage to metaphase II. Following extrusion of two polar bodies, the oocyte was processed for cytogenetic analysis which revealed two separate haploid chromosome sets accompanied by the corresponding polar body chromatin. Tentatively established karyotypes were 23,X and 23,X,ace, respectively. This con...

PURPOSE OF REVIEW To evaluate current and previous findings related to a timely implementation of in-vitro maturation (IVM) of germinal vesicle, metaphase I and metaphase II oocytes with an optimal cryopreservation to determine whether IVM should be attempted prior to (fresh IVM) or IVM after cryopreservation (postthaw IVM). Mitochondrion, chromatin and spindle formation in both groups were int...

The present studies have been undertaken to investigate the interactions that occur between the nucleus and cytoplasm of ovine oocytes at various stages during meiotic maturation. We report that the nucleus of ovine fully grown dictyate stage oocytes can be efficiently removed by a microsurgical enucleation procedure. It is demonstrated that between the initiation of maturation and germinal ves...

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...

Porcine immature oocyte quality (i.e., that of live oocytes at the germinal vesicle stage) was evaluated according to features of the surrounding cumulus, aiming to establish maturational competence of different subpopulations of such cumulus-oocyte complexes. Six subpopulations were identified: A1 (with a dense cumulus), A2 (with a translucent cumulus), B1 (with the corona radiata), B2 (partly...

In oocytes of the newt Pleurodeles waltl, the maternal nuclear protein PwA33 occurs on the lampbrush chromosomes and in some nucleoplasmic particles of the germinal vesicle. PwA33 is a modular protein and we used site-directed mutagenesis to alter the sequences encoding two metal-binding regions, the C3HC4 (or RING finger) and B-box motifs. Several mutant clones were generated and their synthet...

This review compiles present knowledge of the structure and molecular composition of the enigmatic cytoplasmic organelles called accessory nuclei. Most typically, they are found in the perinuclear cytoplasm in oocytes of insects and several other invertebrates. Accessory nuclei originate by budding of the oocyte nucleus (germinal vesicle) and are surrounded by an envelope identical to the nucle...

The present study was undertaken to explore the regulatory mechanisms for meiotic resumption of pig cumulus-oocyte complexes (COCs) by assessing the nuclear status of oocytes, the degree of gap junction cell-to-cell communication and cumulus expansion after culture of various numbers of COCs in 10 microl droplets of medium for 24 h. Gap junction communication was examined by confocal laser scan...