BACKGROUND Shortly after stimulation by the preovulatory surge of luteinizing hormone (LH), oocytes arrested at the late prophase I resume meiosis characterized by germinal vesicle breakdown (GVBD), chromosome condensation, and extrusion of the first polar body in preparation for fertilization and early embryonic development. However, oocytes express few or no LH receptors and are insensitive t...

OBJECTIVES It was aimed to investigate the effects of different doses of follicle stimulating hormone (FSH) and activin A on the growth and maturation of preantral mouse follicles during the in vitro culture. METHODS Preantral follicles (90-100 microm in diameter) were harvested from 6-8 week-old Syrian mice and cultured in TCM199 culture medium for 6 days to see the effect of FSH and Activin...

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...

This study was designed to investigate the effects of α-tocopherol and granulosa cells monolayer on nuclear maturation and cleavage rates of ovine cumulus-oocyte complexes (COCs). The COCs (n = 2814) were matured in maturation medium supplemented with various concentration of α-tocopherol (0, 5, 10, 15 μg/ml), oocytes were incubated at 39 °C with 5 % CO2 for 24 h in three culture systems: (a) m...

As a tumor suppressor homologue during mitosis, Chk2 is involved in replication checkpoints, DNA repair, and cell cycle arrest, although its functions during mouse oocyte meiosis and early embryo development remain uncertain. We investigated the functions of Chk2 during mouse oocyte maturation and early embryo development. Chk2 exhibited a dynamic localization pattern; Chk2 expression was restr...

In mammals, a finite population of oocytes is generated during embryogenesis, and proper oocyte meiotic divisions are crucial for fertility. Sperm-associated antigen 1 (SPAG-1) has been implicated in infertility and tumorigenesis; however, its relevance in cell cycle programs remains rudimentary. Here we explore a novel role of SPAG-1 during oocyte meiotic progression. SPAG-1 associated with me...

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 ...

Cytoplasmic polyadenylation-element-binding protein (CPEB) is a well-characterized and important regulator of translation of maternal mRNA in early development in organisms ranging from worms, flies and clams to frogs and mice. Previous studies provided evidence that clam and Xenopus CPEB are hyperphosphorylated at germinal vesicle breakdown (GVBD) by cdc2 kinase, and degraded shortly after. To...

In the mammalian oocyte, distinct patterns of centromeres and pericentromeric heterochromatin localisation correlate with the gamete's developmental competence. Mouse antral oocytes display two main types of chromatin organisation: SN oocytes, with a ring of Hoechst-positive chromatin surrounding the nucleolus, and NSN oocytes lacking this ring. When matured to MII and fertilised, only SN oocyt...

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, ...