Co-culture of day-5 to day-7 equine embryos in medium with oviductal tissue

Oviductal and uterine embryos were collected from mares at 5 to 7 days following ovulation 1) to evaluate the effects of oviductal tissue explants on in vitro growth and development of equine embryos and 2) to study the morphologic development of equine embryos in culture. Embryos were incubated for 5 days in a medium (control group) or in medium supplemented with oviductal tissue explants (co-culture group). Embryos were evaluated and the media changed daily. Following 5 days in culture, 10 10 (100%) control embryos and 27 29 (93%) co-cultured embryos had doubled in diameter. All embryos that were recovered as morulae developed to the blastocyst stage in culture. By 5 days in culture, 6 10 (60%) control embryos and 19 29 (66%) co-cultured embryos had reached the hatching blastocyst stage of development. By 3 days in culture, significantly more (P<0.05) control embryos versus co-cultured embryos had degenerated (4 10 vs 2 29 , respectively). By 5 days in culture, significantly more (P<0.01) control embryos versus co-cultured embryos had degenerated (6 10 vs. 3 29 , respectively). Embryos cultured with oviductal tissue were sustained longer than embryos cultured in medium alone. Hatching was characterized by the blastocyst squeezing through a small opening in the zona pellucida or by the zona pellucida thinning over approximately half of the blastocyst surface and subsequently disappearing entirely.