These studies were conducted to investigate the effects of GTH, steroids and serums on the in vitro matutation of bovine follicular oocytes and to assess the fertilizing ability of the in vitro matured oocytes. The bovine oocytes recovered from follic...
These studies were conducted to investigate the effects of GTH, steroids and serums on the in vitro matutation of bovine follicular oocytes and to assess the fertilizing ability of the in vitro matured oocytes. The bovine oocytes recovered from follicles 1-3㎜ and 4-6mm in size were cultured for 16hr or 30hr at 38℃ with 5% CO₂ in moist air. In order to assess fertilizing ability of oocytes the in vitro matured oocyteswere transferred to the uterus or oviduct of rabbits inseminated into the uteruswith bull semen 4-6hr before oocyte transfer. 1. After 30hr of culture in m-KRB solution contains FSH and HCG, 411.3% and 25.0% of oocytes matured to metaphase II, respectively. Oocyte maturation was not increased by FSH but was significantly inhibited by HCG as compared with the control (44.2%). 2. The maturation rate (46.3%) of oocytes from 4-6 ㎜ follicles was higher, not significant, than that (31.4%) of 1-3mm follicular oocytes. The maturation of small follicular oocytes was more greatly inhibited by the addition of SIU HCG/㎖ However, this inhibitory effect was significantly improved when the time of HCG exposure shortened to 16hr and FCS instead of BSA was added to m-KRB solution. 3. More than 70% of oocytes reached metaphase II when oocytes were cultured in m-KRB solution containing only 15% (v/v) FCS or 10% (v/v) estrous cow serum, while 53.3% oocytes in m-KRB solution containing BSA. Maturation rate (70∼80%) was increased by the addition of FCS, FSH and steroids as compared with m-KRB containing only BSA (41.3%). 4. A higher fertilization rate (25%) was obtained when oocytes were cultured in m-KRB solution containing FCS, FSH and progesterone, while 8% in m-KRB solution plus BSA. Fertilization rate of oocytes matured in m-KRB plus FCS or estrous cow serum was not higher than that in m-KRB plus BSA but 28.6%o of (4/14) of the fertilized oocytes were cleaved to 2-3 cell stage.