Bovine oocytes cultured in control medium or in medium containing dibutyrylcyclic adenosine monophosphate (dbcAMP) or an inhibitor of cyclic nucleotide phosphodiesterase (3-isobutyl-1-methylxanthine, IBMX) undergo germinal vesicle breakdown (GVBD). On the other hand, mouse oocytes remain arrested at the germinal vesicle (GV) stage when dbcAMP or IBMX is present. When 1 bovine GV stage oocyte is...

In the hermaphrodite ascidian Ciona intestinalis, the egg vitelline coat (VC) controls gamete self-nonself discrimination. Oocytes, after germinal vesicle breakdown, can be fertilized by both self and nonself sperm. However, a barrier to fertilization by self sperm progressively develops in the VC in the 3 hours after germinal vesicle breakdown. During this period, follicle cells attached to th...

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...

BACKGROUND To better understand the differences between in vivo (IVO) and in vitro (IVM) matured oocytes, we studied the chronological changes in cortical granule (CG) distribution and nuclear progression during maturation, and the competence of CG release and embryo development of mouse oocytes matured under different conditions. METHODS Oocytes matured in vivo or in different culture media ...

To determine the effect of gonadal feedback on plasma GTH level, female rainbow trout were ovariectomized at three stages at the end of the reproductive cycle: at the end of vitellogenesis, during germinal vesicle migration and during the post-ovulatory period. A group of controls and one of castrates in each experiment were given an injection of physiological salt solution, and a third group o...

The Drosophila gene ald encodes the fly ortholog of mps1, a conserved kinetochore-associated protein kinase required for the meiotic and mitotic spindle assembly checkpoints. Using live imaging, we demonstrate that oocytes lacking Ald/Mps1 (hereafter referred to as Ald) protein enter anaphase I immediately upon completing spindle formation, in a fashion that does not allow sufficient time for n...

In order to achieve developmental competence, porcine oocytes must undergo both nuclear and cytoplasmic maturation. Nuclear maturation results from breakdown of the germinal vesicle (GV) and progression of meiosis to metaphase II (MII). Cytoplasmic maturation is the accumulation, within the oocyte’s cytoplasm, of products necessary for fertilization, cleavage and development, prior to activatio...

To improve controlled reproduction of Eurasian perch Perca fluviatilis, the criteria for the evaluation of final oocyte maturation stages were revised. The new classification covers six preovulatory maturational stages (I -VI) from the end of vitellogenesis to germinal vesicle breakdown (GVBD) and was based on macroscopic changes of preovulatory oocytes (position of the germinal vesicle, GVBD, ...

Previous work has demonstrated that the Xenopus protooncogene mosxe can induce the maturation of prophase-arrested Xenopus oocytes. Recently, we showed that mosxe can transform murine NIH3T3 fibroblasts, although it exhibited only 1-2% of the transforming activity of the v-mos oncogene. In this study we have investigated the ability of the v-mos protein to substitute for the mosxe protein in st...

Fully grown mouse oocytes isolated from large antral follicles and cultured in vitro complete their maturation up to the second metaphase with extrusion of the first polar body (1PB) with a 40/50 proportion (80%). When their cytoplasmic volume is, however, reduced before the onset of culture, the frequency of oocytes completing maturation gradually decreases. In the half oocytes, 66% (33/50) ex...