The aim of this study was to investigate the role of progesterone in the meiotic resumption of porcine oocytes. Progesterone production and progesterone receptor (PR) immunoreactivity in cumulus cells were not detected in porcine cumulus-oocyte complexes (COC) when observations were made either just after collection from the follicles or after 28 h cultivation without LH and FSH. However, the a...

The tyrosine phosphorylation/dephosphorylation of p34cdc2 was estimated by immunoblotting with antiphosphotyrosine antibody during meiotic maturation of Xenopus oocytes. At the time of germinal vesicle breakdown (GVBD), p34cdc2 is tyrosine dephosphorylated whereas a p42 protein, which might correspond to a MAP2 kinase, becomes tyrosine phosphorylated. No modification in the level of tyrosine ph...

Background: Polycystic ovary syndrome (PCOS) is characterized by chronic anovulation and hyperandro genism and affects approximately 5-10% of women of reproductive age. In vitro maturation (IVM) of mammalian oocytes has become an efficient method to produce mature oocytes in order to use in assisted reproductive techniques such as in vitro fertilization (IVF), intra cytoplasmic sperm injection ...

In mammalian cells, 5-methylcytosine (5-meC) can be transformed into 5-hydroxymethylcytosine (5-hmC) by the methylcytosine dioxygenase TET proteins (TET1, TET2 and TET3). Thymine DNA glycosylase (TDG), a downstream enzyme of TET proteins, not only functions in base excision repair, but also acts as a key enzyme that participates in active DNA demethylation. Here we microinjected exogenous TDG-m...

In Xenopus oocytes, the mos proto-oncogene product is required during meiosis I for the activation of maturation promoting factor (MPF) and the subsequent breakdown of the germinal vesicle (GVBD). In addition, the mos product has been shown to be a candidate "initiator" of meiotic maturation and is an active component of cytostatic factor (CSF), an activity responsible for metaphase II arrest. ...

The role of Raf and MAPK (mitogen-activated protein kinase) during the maturation of Xenopus oocytes was investigated. Treatment of oocytes with progesterone resulted in a shift in the electrophoretic mobility of Raf at the onset of germinal vesicle breakdown (GVBD), which was coincident with the activation of MAPK. Expression of a kinase-defective mutant of the human Raf-1 protein (KD-RAF) inh...

The ability of different isoforms of follicle stimulating hormone (FSH) to induce the resumption of meiosis in cultured mouse oocytes was evaluated. Oocytes were cultured in the presence of hypoxanthine to prevent spontaneous resumption of meiosis. Using serial dilutions of the isoform fractions representing less acidic isoforms (pI 6. 43-5.69), mid-acidic (pI 5.62-4.96) and acidic (pI 4.69-3.7...

We have measured the levels of cyclin mRNAs and polypeptides during oogenesis, progesterone-induced oocyte maturation, and immediately after egg activation in the frog, Xenopus laevis. The mRNA for each cyclin is present at a constant level of approximately 5 x 10(7) molecules per oocyte from the earliest stages of oogenesis until after fertilization. The levels of polypeptides show more comple...

background: the aim of this study was to assess effects of cysteamine as an anti-oxidant on rate of in vitro maturation of oocyte and determination of its effects on spindle size and shape. methods: pre-mature mice were primed with pregnant mare stimulating gonadotrophin (pmsg) and germinal vesicle (gv) stage oocytes were obtained 48 h after. the oocytes were cultured in tissue culture medium (...

It is demonstrated that the microinjection of cytoplasm from competent, fully grown oocytes can induce germinal vesicle breakdown in meiotically incompetent growing oocytes. Injection of cytoplasm from oocytes at methaphase I had a similar effect. The maturation in injected growing oocytes was arrested at the premetaphase or metaphase I stage. Induction of germinal vesicle breakdown by cytoplas...