Heat stress is one of the main reasons for reproductive performance decrease in cattle, resulting in severe economic losses. The aim of this study was to evaluate the effect of heat stress during maturation, fertiliza...Heat stress is one of the main reasons for reproductive performance decrease in cattle, resulting in severe economic losses. The aim of this study was to evaluate the effect of heat stress during maturation, fertilization and development of in vitro produced bovine embryos. Cumulus oocyte complexes (COCs) were obtained by follicular puncture from slaughterhouse ovaries and after identification, were divided into four groups: control (CG), exposed 1 (EG1), exposed 2 (EG2), and exposed 3 (EG3). The oocytes of the group CG and CG3 were cultured at 38°C and the oocytes of group EG1 and EG2 were cultured at 40°C during the maturation period (24 hours at 5% CO2 in air). After the maturation period, oocytes of group CG, EG1, EG2, and EG3 were fecundated with frozen thawed semen. The oocytes of CG, EG2 and EG3 groups were cultured at 38°C, and the group EG1 was cultured at 40°C (18 hours at 5% CO2 in air). After that, the CG and EG2 groups were cultured in SOF at 38°C and the groups EG1 and EG3 at 40°C during embryonic development. The embryos were evaluated for cleavage, morula and blastocyst rates by optical microscopy. In control (CG) and EG3 groups, the oocytes showed uniform expansion of cumulus cells, classified as moderate to high, with brown color and uniform appearance of the ooplasm. In the oocytes exposed to 40°C (EG1 and EG2) we observed a decrease in the expansion of cumulus cells, and the same showed rounded appearance and retraction of the ooplasm with dark coloration. The control group (CG) had 68.23% ± 2% of cleavage, 50.16% ± 2% morulas, and 43.28% ± 1% blastocysts. Whereas the EG2 had 31.46% ± 2% cleavage, 35.64% ± 2% morula, and no blastocysts development. The EG3 had 3.7% ± 2% cleavage, and no embryo production. These data suggest that in all stages of exposure to heat stress, the embryos and the gametes are susceptible, leading to a decrease in embryonic development.展开更多
Fertilization in mammals requires the successful completion of a sequence of steps, starting with the transport of gametes in the reproductive tract and ending with sperm-egg membrane fusion to produce a zygote. Altho...Fertilization in mammals requires the successful completion of a sequence of steps, starting with the transport of gametes in the reproductive tract and ending with sperm-egg membrane fusion to produce a zygote. Although some integrin subunits are known to be associated with the plasma membrane of some mammalian oocytes and spermatozoa, the presence of α6 integrin on bovine oocytes with intact zona pellucida has not been reported. The present study was undertaken to evaluate the expression of α6 integrin subunit in bovine oocyte and to determine if in vitro binding to the zona pellucida and fertilization were affected by treating oocytes with α6 integrin subunit antibody. The α6 integrin subunit was identified on the bovine oocyte by immunocytochemistry. In vitro fertilization was significantly decreased when in vitro matured bovine oocytes were pre-incubated with α6 integrin subunit antibody at concentration 5 and 20 μg/mL, and spermoocyte binding increased. These studies demonstrated the presence of α6 integrin subunit on bovine oocyte, and its importance in fertilization and polyspermy.展开更多
文摘Heat stress is one of the main reasons for reproductive performance decrease in cattle, resulting in severe economic losses. The aim of this study was to evaluate the effect of heat stress during maturation, fertilization and development of in vitro produced bovine embryos. Cumulus oocyte complexes (COCs) were obtained by follicular puncture from slaughterhouse ovaries and after identification, were divided into four groups: control (CG), exposed 1 (EG1), exposed 2 (EG2), and exposed 3 (EG3). The oocytes of the group CG and CG3 were cultured at 38°C and the oocytes of group EG1 and EG2 were cultured at 40°C during the maturation period (24 hours at 5% CO2 in air). After the maturation period, oocytes of group CG, EG1, EG2, and EG3 were fecundated with frozen thawed semen. The oocytes of CG, EG2 and EG3 groups were cultured at 38°C, and the group EG1 was cultured at 40°C (18 hours at 5% CO2 in air). After that, the CG and EG2 groups were cultured in SOF at 38°C and the groups EG1 and EG3 at 40°C during embryonic development. The embryos were evaluated for cleavage, morula and blastocyst rates by optical microscopy. In control (CG) and EG3 groups, the oocytes showed uniform expansion of cumulus cells, classified as moderate to high, with brown color and uniform appearance of the ooplasm. In the oocytes exposed to 40°C (EG1 and EG2) we observed a decrease in the expansion of cumulus cells, and the same showed rounded appearance and retraction of the ooplasm with dark coloration. The control group (CG) had 68.23% ± 2% of cleavage, 50.16% ± 2% morulas, and 43.28% ± 1% blastocysts. Whereas the EG2 had 31.46% ± 2% cleavage, 35.64% ± 2% morula, and no blastocysts development. The EG3 had 3.7% ± 2% cleavage, and no embryo production. These data suggest that in all stages of exposure to heat stress, the embryos and the gametes are susceptible, leading to a decrease in embryonic development.
文摘Fertilization in mammals requires the successful completion of a sequence of steps, starting with the transport of gametes in the reproductive tract and ending with sperm-egg membrane fusion to produce a zygote. Although some integrin subunits are known to be associated with the plasma membrane of some mammalian oocytes and spermatozoa, the presence of α6 integrin on bovine oocytes with intact zona pellucida has not been reported. The present study was undertaken to evaluate the expression of α6 integrin subunit in bovine oocyte and to determine if in vitro binding to the zona pellucida and fertilization were affected by treating oocytes with α6 integrin subunit antibody. The α6 integrin subunit was identified on the bovine oocyte by immunocytochemistry. In vitro fertilization was significantly decreased when in vitro matured bovine oocytes were pre-incubated with α6 integrin subunit antibody at concentration 5 and 20 μg/mL, and spermoocyte binding increased. These studies demonstrated the presence of α6 integrin subunit on bovine oocyte, and its importance in fertilization and polyspermy.
