Meiotic maturation in mammalian oocytes is a complex process which involves extensive rearrangement of microtubules, actin filaments and chromosomes. Since cytoskeletal elements are sensitive to disruption by heat shock, series experiments were performed determine whether physiologically relevant shock disrupts the progression oocyte through meiosis, fertilization zygote formation. Cumulus-oocyte complexes cultured at 38.5, 40.0 or 41.0 degrees C for first 12 h maturation. Incubation during...

Various pathological stimuli such as radiation, environmental toxicants, oxidative stress, and heat shock can initiate apoptosis in mammalian oocytes. Experiments were performed to examine whether mediated by group II caspases is the cause for disruption of oocyte function applied during maturation cattle. Bovine cumulus-oocyte complexes (COCs) cultured at 38.5, 40, or 41°C first 12 h maturation. Incubation last 10 maturation, fertilization, embryonic development 38.5°C 5% (v/v) CO2 all...

The fertility of dairy cows decreases during the summer and remains low cooler autumn although animals are no longer under heat stress. aim this study was to characterize a delayed effect stress on oocyte quality in improve by enhanced removal follicles damaged previous summer. Lactating (n = 16) were subjected In autumn, ovarian (3-7 mm diameter) aspirated an ultrasound-guided procedure four consecutive oestrous cycles. Follicles from control day 4 treated days 4, 7, 11 15 each cycle. All...

The relationship between phosphorylation ratio ([ATP])/[ADPl[Pi], phosphocreatine (PCr)/Pi, and ATPase activity was determined for isolated rat heart mitochondria, the use of and/or PCr/Pi as bioenergetic indices (Chance, B.,

We examined the association between season and expression of genes involved in early embryonic development with an emphasis on cleavage rate timing first cleavage. In Exp. 1, oocytes were aspirated during cold (Dec-Apr) hot (May-Nov) seasons. Matured chemically activated cultured vitro. The developmental peak to two- four-cell stages occurred earlier, a higher proportion first-cleaved embryos, relative (P<0.01). 2, time-lapse system was employed characterize delayed noted for season....

Physiologicalperturbations of bovine follicle-enclosed oocytes during the lengthy period follicular development can lead to reduced oocyte developmental competence. It is suggested that heat stress-induced alterations in germinal vesicle (GV)-stage are further expressed transcriptional levels genes involved maturation and early embryonic development. Bovine were collected cold (December–April) hot (May–November) seasons, matured, fertilized, cultured vitro. The percentage fertilized cleaving...

The aim of this study was to characterize the immediate effects heat stress on plasma FSH and inhibin concentrations, its involvement in follicular dynamics during a complete oestrous cycle, examine possible delayed effect development. Holstein dairy cows were synchronized randomly assigned either cooled (n = 7) or heat-stressed 6) treatment groups. During control cows, which cooled, maintained normothermia, whereas exposed direct solar radiation, developed hyperthermia. At end cycle...

Luteal regression is initiated by prostaglandin F2α (PGF2α). In domestic species and primates, demise of the corpus luteum (CL) enables development a new preovulatory follicle. However, during early stages cycle, which are characterized massive neovascularization, CL refractory to PGF2α. Our previous studies showed that endothelin-1 (ET-1), produced endothelial cells lining these blood vessels, plays crucial role PGF2α-induced luteolysis. Therefore, in this study, we compared effects PGF2α...

Sphingosine 1-phosphate (S1P) is a sphingolipid metabolite that can block apoptosis by counteracting the proapoptotic effects of ceramide. Experiments were performed to evaluate whether S1P blocks disruption in oocyte developmental competence caused heat shock. Cumulus-oocyte complexes (COCs) placed maturation medium and cultured at 38.5 or 41 degrees C for first 12 h maturation. Incubation during last 10 maturation, fertilization, embryonic development C. Heat shock reduced cleavage rate,...

In light of the intensive genetic selection for high milk production and onset global warming, it seems that reduced fertility lactating cows during summer will worsen in coming years. Although not entirely clear, mechanism appears to be multifactorial nature. It includes alterations follicular development, depression dominance, impairment steroidogenesis gonadotropin secretion. Heat-induced perturbations physiology follicle-enclosed oocyte have also been documented, expressed by impaired...

Vitrification is becoming the method of choice for embryo cryopreservation. Nevertheless, major problems are still associated with this process such as chemical toxicity and osmotic stress well risk liquid nitrogen (LN) contamination. An innovative vitrification that combines LN slush sealed pulled straws (SPS) was employed to achieve a high cooling rate, enabling reduction in cryoprotectant concentration. Open were at both ends prevent direct contact LN. Ultrarapid murine embryos 32...