نتایج جستجو برای: meiosis resumption

تعداد نتایج: 11994  

Journal: :Molecular human reproduction 2009
Meijia Zhang Hong Ouyang Guoliang Xia

Fully grown mammalian oocytes are arrested at the first meiotic prophase until a surge of gonadotrophin at the mid-cycle. The actions of gonadotrophins, follicle stimulating hormone (FSH) and luteinizing hormone (LH), on oocyte meiotic resumption are believed to be mediated in large part through increasing the production of cyclic adenosine 3',5'-monophosphate and subsequent activation of mitog...

Journal: :Developmental biology 2008
Jing Chen Stephen M Downs

We have previously shown that AMP-activated protein kinase (AMPK) can induce the resumption of meiosis in mouse oocytes maintained in meiotic arrest in vitro. The present study was carried out to determine whether AMPK activation is involved in hormone-induced maturation. Follicle-stimulating hormone (FSH) and the EGF-like peptide, amphiregulin (AR), are potent inducers of maturation in cumulus...

Journal: :Biology of reproduction 2016
Jeremy R Egbert Tracy F Uliasz Leia C Shuhaibar Andreas Geerts Frank Wunder Robin J Kleiman John M Humphrey Paul D Lampe Nikolai O Artemyev Sergei D Rybalkin Joseph A Beavo Matthew A Movsesian Laurinda A Jaffe

The meiotic cell cycle of mammalian oocytes in preovulatory follicles is held in prophase arrest by diffusion of cGMP from the surrounding granulosa cells into the oocyte. Luteinizing hormone (LH) then releases meiotic arrest by lowering cGMP in the granulosa cells. The LH-induced reduction of cGMP is caused in part by a decrease in guanylyl cyclase activity, but the observation that the cGMP p...

2010
Johannes Backs Paula Stein Thea Backs Francesca E. Duncan Chad E. Grueter John McAnally Xiaoxia Qi Richard M. Schultz Eric N. Olson

Fertilization triggers a rise in intracellular Ca concentration ([Ca]i) in the egg that initiates a series of events known as egg activation. These events include cortical granule exocytosis that establishes a block to polyspermy, resumption of meiosis, and recruitment of maternal mRNAs into polysomes for translation. Several calcium-dependent proteins, including calcium/calmodulin-dependent pr...

Journal: :Reproduction in domestic animals = Zuchthygiene 2012
K Reynaud M Chebrout C Tanguy-Dezaux G de la Villéon S Chastant-Maillard

In canine species, in vitro maturation (IVM) rates of oocytes collected from anoestrous ovaries are low (<20%). Several IVM media have been tested without significant improvements. A critical step in the evaluation of culture conditions is the observation of the meiotic stage reached by the oocytes. The present study was designed to investigate the chromatin patterns of in vitro matured oocytes...

Journal: :Reproduction 2005
Elena Ibáñez David F Albertini Eric W Overström

With the aim of investigating the effects of oocyte genotype and activating stimulus on the timing of nuclear events after activation, oocytes collected from hybrid B6D2F1, inbred C57BL/6 and outbred CF-1 and immunodeficient nude (NU/+) females were activated using ethanol or strontium and fixed at various time-points. Meiotic status, spindle rotation and second polar body (PB2) extrusion were ...

Journal: :Development 2011
Melina Gaffré Alain Martoriati Naima Belhachemi Jean-Philippe Chambon Evelyn Houliston Catherine Jessus Anthi Karaiskou

In fully grown oocytes, meiosis is arrested at first prophase until species-specific initiation signals trigger maturation. Meiotic resumption universally involves early activation of M phase-promoting factor (Cdc2 kinase-Cyclin B complex, MPF) by dephosphorylation of the inhibitory Thr14/Tyr15 sites of Cdc2. However, underlying mechanisms vary. In Xenopus oocytes, deciphering the intervening c...

2009

Butyrolactone I (BL I), a potent and specific inhibitor of cyclin-dependent kinases, was shown to block germinal vesicle breakdown (GVBD) in porcine oocytes in a concentration-dependent manner. GVBD was almost totally inhibited over the course of 44 h of culture when 100 pM BL I was included in TCM 199 containing either 3 mg/ml BSA or 5 % fetal calf serum (FCS). In contrast, 50 pM BL 1 was full...

2015
Radek PROCHAZKA Milan BLAHA

In vivo, resumption of oocyte meiosis occurs in large ovarian follicles after the preovulatory surge of luteinizing hormone (LH). The LH surge leads to the activation of a broad signaling network in mural granulosa cells equipped with LH receptors. The signals generated in the mural granulosa cells are further augmented by locally produced peptides or steroids and transferred to the cumulus cel...

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