Cytokeratins have previously been shown to exist in the Xenopus oocyte cortex. Using three monoclonal antibodies against cytokeratins, we follow the appearance of cytokeratin-containing filaments, and their changes in distribution during oocyte differentiation and maturation. Cytokeratin-containing filaments are shown to change dramatically in distribution in the oocyte during its ontogeny.

Prediction and improvement of oocyte competence are two critical issues in assisted reproductive technology to improve infertility therapy. The lack of reliable and objective predictors of oocyte developmental competence for oocyte/embryo selection during in vitro fertilization hampers the effectiveness of this technology. Likewise, the low pregnancy rate resulting from in vitro maturation of h...

INTRODUCTION Fertility is referred to the capability for having offspring and can be evaluated by fertility rate. Women's fertility is strictly dependent on individual's age. The fertility peak occurs in the early 20s, and it starts to decline in the third and fourth decades of life (falling sharply after age 35). AIM The aim of this work is to review the available data concerning fertility i...

Generation of reactive oxygen species (ROS) is associated with final stages of follicular development and ovulation in mammals. The human chorionic gonadotropin (hCG) mimics the action of luteinizing hormone and triggers follicular development and ovulation. However, it remains unclear whether hCG induces generation of ROS, if yes, whether hCG-mediated increased level of ROS could induce meioti...

Brief exposure to some pesticides, applied during a sensitive window for the neural regulation of ovulation, will block the preovulatory surge of LH and, thus, delay ovulation. Previously, we have shown that a single i.p. injection of 50 mg/kg of thiram, a dithiocarbamate fungicide that decreases norepinephrine synthesis, on proestrus (1300 h) suppresses the LH surge and delays ovulation for 24...

background: it is important to protect oocytes and embryos from oxidative stress in the culture medium. melatonin has been shown to be a direct free radical scavenger. objective: effect of melatonin during in vitro oocyte maturation, fertilization and embryo development of mouse oocytes was evaluated. materials and methods: oocytes from supper-ovulated mouse were divided to two groups: cumulus ...

In Drosophila, a single oocyte develops within a 16-cell germline cyst. Although all 16 cells initiate meiosis and undergo premeiotic S phase, only the oocyte retains its meiotic chromosome configuration and remains in the meiotic cycle. The other 15 cells in the cyst enter the endocycle and develop as polyploid nurse cells. A longstanding goal in the field has been to identify factors that are...

In the growing follicle, communication between the oocyte and its surrounding follicular cells is essential for normal oocyte and follicular development. Maturation of the fully grown oocyte in vivo is associated with the loss of cumulus cell-oocyte gap junctional communication, preventing entry of meiotic-modulating factors such as cAMP into the oocyte. We have previously shown that oocyte and...

Spermidine is a naturally occurring polyamine involved in multiple biological processes, including DNA metabolism, autophagy and aging. Like other polyamines, spermidine is also indispensable for successful reproduction at several stages. However, a direct influence on the actual fertilization process, i.e., the fusion of an oocyte with a spermatocyte, remains uncertain. To explore this possibi...