PARTHENOGENETIC DEVELOPMENT OF ACTIVATED INVITRO MATURED BOVINE OOCYTES

Bovine oocytes matured in vitro for 26 hours were electrically stimula ted 1) by a single pulse (Treatment A) ; 2) by 3 pulses 30 minutes apa rt (Treatment B) ; 3) by a single pulse followed by 5 minutes of incub ation in the stimulation medium (Treatment C); or 4) by a single pulse at 27 hours of maturation (Treatment D). The oocytes were then cultur ed for up to 8 days to assess parthenogenetic activation and developme nt. Each electrical stimulation consisted of a 60-mus square wave puls e of 2.5 or 3.6 kV/cm. Treatment A was less effective than the other t reatments (P<0.05), activating 47 or 59% of oocytes at 2.5 or 3.6 kV/c m, respectively. However, there were no differences due to voltage nor among the other treatments, which activated 64 to 78% of the oocytes. The cleavage rate, 28 to 38%, was not affected by the activation trea tment, but development to the 8-cell stage or beyond was greater after activation with the higher voltage. While the numbers of morulae or b lastocysts resulting from any given treatment were too small to suppor t meaningful statistical comparison, the results indicate that bovine parthenogenotes produced in vitro are capable of development to the bl astocyst stage.