Authors: Sema BİRLER, Serhat PABUÇÇUOĞLU, Serhat ALKAN, Mithat EVECEN, İ. Kamuran İLERİ
Abstract: Primer oocytes (n=520) collected from ovaries of slaughtered cows were divided into 3 groups, and matured at 39ºC with 95-100% humidity and under a gas mixture of 5% O 2 , 5% CO 2 and 90% N 2 for 22, 24 and 26 hours. Modified Parker's Medium (MPM) supplemented with FSH and 20% ECS was used as maturation medium. At the end of these periods, oocytes (22 h.=122, 24 h.=143 and 26 h.=255) were taken into Tyrode-lactate medium supplemented with BSA, heparin and PHE, and frozen-thawed bull semen was add after swim-up procedure (10µl@400.000 spermatozoa/30-35 oocytes). Oocytes matured in 3 groups were kept with spermatozoa for 14, 16, 18, 20, 22 and 24 hours. At the end of these time periods all oocytes were fixed, stained and examined by phase-contrast microscope. In total 42 (72.4%), 38 (69.1%) and 100 (84.7%) oocytes relating to the maturation groups, male and female pronuclei were synchronised. Difference between the 26 h. group and the other groups was highly significant (c 2 , p<0.001). In 25 (59.5%), 29 (76.3%) and 74 (74.0%) oocytes, pronuclei were reached the 4th and 5th stages, respectively, according to the maturation groups. The low rate in 22 h. group was highly significant relating to the other groups (c 2 , p<0.001), and the high rate in 24 h. group was significantly important relating to the 26 h. group (c 2 , p<0.01).
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