PARTHENOGENETIC DEVELOPMENT OF BOVINE OOCYTES MATURED IN-VITRO FOR 24-HR AND ACTIVATED BY ETHANOL AND CYCLOHEXIMIDE

This research was undertaken to improve development of parthenogenetic embryos following various combined treatments of ethanol and cyclohex imide. In Experiment 1 in vitro matured oocytes (IVM, 24 hr) were trea ted with 7% ethanol for 5 min followed by incubation in 10 mu g/ml cyc loheximide in Medium 199 for 0 (control), 5, 10, and 20 hr. Developmen t to 2-8 cells following culture for 3 days was similar among treated groups (32-41%; P > 0.05), which was higher than that of controls (6%; P < 0.05). Experiment 2 compared pre-ethanol exposures for 0, 1, 2.5, and 5 min, followed by 5 hr cycloheximide treatment on activation dev elopment. One- to 5-min groups resulted in 42-44% cleavage contrasted to 1-12% for controls (P < 0.05). Experiment 3 examined the effect on oocyte development of ethanol and different concentrations of cyclohex imide (0, 1, 5, and 10 mu g/ml). Cleavage to 2-8 cells was similar amo ng the 5 and 10 mu g/ml cycloheximide groups (36% and 42%, P > 0.05) b ut lower (P < 0.05) for the 1 mu g/ml group (24%) and the controls (2- 13%). When 5 mu g/ml cycloheximide was used (Experiment 4), pre-exposu re to ethanol (1, 2.5, and 5 min) resulted in more oocytes cleaved (38 -41%) than in the cycloheximide alone group (0%) or the control (0%, P < 0.05). Experiment 5 tested blastocyst development of the activated oocytes with or without cytochalasin B treatment. Oocytes developed to blastocysts were 0%, 14%, 3%, and 3% (P < 0.05), respectively, for co ntrol, treatment with ethanol and cycloheximide in the presence, or ab sence of cytochalasin B, or electrical pulse plus cycloheximide. In co nclusion, the combined ethanol and cycloheximide treatment supported h igh rates of parthenogenetic development using 24 hr IVM bovine oocyte s. Blastocyst rate was significantly higher when cytochalasin B was ad ded to the combined activation regimen. (C) 1994 Wiley-Liss, Inc.