OVIDUCTAL AND UTERINE INFLUENCE ON THE DEVELOPMENT OF DAY-2 EQUINE EMBRYOS IN-VIVO AND IN-VITRO

The objective of this experiment was to contrast the influence of the oviductal and uterine environments on development of Day-2 embryos. Em bryos were transferred to oviducts or uteri of synchronous recipient m ares, or were incubated in oviductal co-culture, in uterine co-culture or in defined culture medium. Significantly more (P < 0.02) embryos t ransferred to the oviduct versus the uterus survived until Day 11 afte r ovulation (5/7 vs 0/7, respectively). Significantly more (P < 0.001) embryos developed to expanded and hatched blastocysts in uterine co-c ulture than in culture medium (6/7 vs 0/7, respectively). The rate of embryo development to expanded blastocysts was not significantly diffe rent (P > 0.1) in oviductal co-culture versus uterine co-culture (3/7 vs 6/7, respectively), or in oviductal co-culture versus culture in me dium (3/7 vs 0/7, respectively). Three of 7 and 6 of 7 embryos develop ed to hatched blastocysts greater than 2000 mum in diameter during ovi ductal and uterine co-culture, respectively, while 0 of 7 embryos cult ured in medium expanded to greater than 500 mum in diameter. Proportio ns of embryos that developed for at least 9 days