Microinjection of approximately 0.3 mug of calcium into maturing oocytes of Rana pipiens after nuclear dissolution resulted in cleavage-like constrictions, cortical granule breakdown, and formation of a structure resembling a two-cell embryo. Mg2+, Na+, or K+ did not induce any of these reactions. Larger amounts of Ca2+-induced contraction over the entire surface of oocytes or eggs, but did not...

The first meiotic cell division (meiotic maturation) of the dictyate stage of mouse oocytes, removed from the follicle, resumes spontaneously in vitro. This study indicates that estramustine phosphate reversibly blocks meiotic maturation by inhibiting germinal vesicle breakdown. Oocyte cryostat sections were stained with anti-tubulin and two antibodies (anti-MAP1: JA2 and 5051) which decorated ...

Maturation-promoting factor causes germinal vesicle breakdown when injected into Xenopus oocytes and can induce metaphase in a cell-free system. The cell-free assay was used to monitor maturation-promoting factor during its purification from unfertilized Xenopus eggs. Ammonium sulfate precipitation and six chromatographic procedures resulted in a preparation purified greater than 3000-fold that...

The starfish oocyte is relatively clear optically, and its nucleus, termed the germinal vesicle, is large. These characteristics allowed studies by confocal microscopy of germinal vesicle breakdown during maturation in living oocytes. Three fluorescent probes for cytoplasmic components were used: fluorescein 70 kDa dextran, which does not cross the nuclear pore of immature oocytes and probably ...

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 ...

a:4:{s:10:"Background";s:206:"The aim of the present study was to investigate the role of progesterone on the developmental competence of cumulus-oocyte complexes (COCs) and cumulus-denuded oocytes (CDOs) at germinal vesicle (GV) stage.";s:19:"MaterialsAndMethods";s:485:"GV oocytes of pregnant mare's serum gonadotropin (PMSG)-primed prepubertal mice were divided into two groups: CDOs and COCs. ...

The resumption of the meiotic cycle (maturation) induced by 1-methyladenine in prophase-arrested starfish oocytes is indicated by the breakdown of the germinal vesicle and is characterized by the increased sensitivity of the Ca2+ stores to inositol 1,4,5-trisphosphate (InsP3) to InsP3 starting at the animal hemisphere (where the germinal vesicle was originally located) and propagating along the...