BOVINE PARTHENOGENETIC BLASTOCYSTS FOLLOWING IN-VITRO MATURATION AND OOCYTE ACTIVATION WITH ETHANOL

The appropriate in vitro bovine oocyte maturation and ethanol activati on conditions for preimplantation bovine embryo parthenogenetic develo pment to the blastocyst stage were investigated. A 7% ethanol concentr ation significantly enhanced (P<0.05) the proportion of activated, in vitro-matured bovine oocytes (7% ethanol, 83.4 +/- 3.2% versus 0% etha nol, 63.9 +/- 2.0%). The proportion of activated oocytes was significa ntly higher (P<0.05) by treatment with 7% ethanol for a minimum of 2 m inutes (2 minutes, 89.8 +/- 4.0% versus 0.5 minutes 63.4 +/- 4.9%). Oo cyte maturation for periods ranging from 30, 34, 38 and 44 hours resul ted in a significant increase (P<0.05) in the proportion of activated oocytes, and in oocytes displaying 2 or 3 pronuclei versus oocytes mat ured for 26 hours. The proportion of cleaved, activated oocytes (2-cel l stage), 4 -cell stage and parthenogenetic morula/blastocysts was sig nificantly higher (P<0.05) within the 34-hour oocyte maturation treatm ent group. Although the 44-hour oocyte maturation treatment group disp layed the highest proportion of activated oocytes with 2 pronuclei, it did not display the highest cleavage frequency, possibly due to the e ffects of postovulatory aging. Several morphologically normal partheno genetic bovine blastocysts developed from oocytes that were in vitro m atured for 34 hours. The ability to produce such parthenogenetic embry os will eventually facilitate investigation into the role(s) of the ma ternal and paternal genomes during bovine early development.