Cell division is inherently mechanical, with cell mechanics being a critical determinant governing the cell shape changes that accompany progression through the cell cycle. The mechanical properties of symmetrically dividing mitotic cells have been well characterized, whereas the contribution of cellular mechanics to the strikingly asymmetric divisions of female meiosis is very poorly understoo...

Background: Successful in vitro maturation (IVM) of oocytes is an important step for production of livestock through assisted reproductive techniques including somatic cell nuclear transfer (SCNT). Obtaining an optimal duration for maturation of oocyte is essential, since over exposure to maturation medium results in oocyte aging, while under exposure leads to production of immature incompetent...

BACKGROUND The use of immature oocytes is limited to cases where these are the only available oocytes, and they are usually only microinjected with sperm after having undergone maturation in vitro. This study compares the outcome of injection of sperm into metaphase I oocytes immediately after their denudation (MI) performed 2 h after their retrieval, with the outcome of injection of sperm into...

Background: Parthenogenetic activation is a possible way to produce homogeneous embryos with the some ploidy. Probably such embryos could be used in other areas of biotechnology. Calcium signals are known as important regulators of oocyte activation. Extracellular calcium is required for initiation of meiotic resumption and development. Calcium ionophore A23187 is known to elevate intracellular...

Increased glucocorticoid levels, due to medical therapy or stress-related, may affect reproduction via the hypothalamus-pituitary-axis or directly at the oocyte level. We examined the effects of natural (corticosterone) or synthetic (dexamethasone) glucocorticoids on mouse oocyte maturation and underlying changes in extracellular signal-regulated kinase (ERK) phosphorylation patterns. Fertiliza...

Cumulus cells (CC) surround the oocyte and are coupled metabolically through regulation of nutrient intake. CC removal before in vitro maturation (IVM) decreases bovine oocyte developmental competence without affecting nuclear meiotic maturation. The objective was to investigate the influence of CC on oocyte cytoplasmic maturation in relation to energy metabolism. IVM with either cumulus-enclos...

OBJECTIVE To evaluate the influence of ovarian follicular dominance on the outcome of oocyte in-vitro maturation. METHODS This retrospective cohort study included 21 patients with polycystic ovaries or polycystic ovary syndrome (Rotterdam criteria, 2004) subjected to 24 invitro maturation (IVM) cycles between October 2015 and January 2017. Patients undergoing IVM received minimal gonadotropin...

The universal signal for egg activation at fertilization is a rise in cytoplasmic Ca(2+) with defined spatial and temporal kinetics. Mammalian and amphibian eggs acquire the ability to produce such Ca(2+) signals during a maturation period that precedes fertilization and encompasses resumption of meiosis and progression to metaphase II. In Xenopus, immature oocytes produce fast, saltatory Ca(2+...

OBJECTIVE To investigate the oocyte quality in patients with severe ovarian hyperstimulation syndrome (OHSS). DESIGN Self-controlled clinical study. SETTING University teaching hospital. PATIENT(S) Twenty-two patients from our assisted reproductive technology (ART) program who developed severe OHSS during their first controlled ovarian hyperstimulation for IVF or intracytoplasmic sperm in...

Nuclear reprogramming of differentiated cells can be induced by oocyte factors. Despite numerous attempts, these factors and mechanisms responsible for successful reprogramming remain elusive. Here, we identify one such factor, necessary for the development of nuclear transfer embryos, using porcine oocyte extracts in which some reprogramming events are recapitulated. After incubating somatic n...