DEVELOPMENT TO BLASTOCYSTS OF ONE-CELL TO 2-CELL EQUINE EMBRYOS AFTERCOCULTURE WITH UTERINE TUBAL EPITHELIAL-CELLS

Development of 1- to 2-cell in vivo fertilized equine embryos cultured with or without uterine tubal epithelial cells (UTEC) was studied. On e- to 2-cell embryos (n = 26) were collected surgically from the uteri ne tubes of pony mares 1 day after ovulation. Four- to 8-cell embryos (n = 9) were collected 2 days after ovulation. Presumptive zygotes and 2-cell embryos were cultured with (n = 17) or without (n = 9) UTEC, a nd all 4- to 8-cell embryos were cocultured with UTEC as positive cont rols. Uterine tubal epithelial cells were used as cell suspensions wit hin 2 weeks after initiation of cultures. Embryos were cultured to bla stocysts or until the embryo had morphologic degeneration. Six presump tive zygotes failed to cleave in vitro. Development to blastocysts of 1-cell (4 of 11) and 2-cell (2 of 6) embryos cocultured with UTEC was similar. Coculture of 1- to 2-cell embryos with UTEC significantly (P = 0.05) improved development to blastocysts, compared with culture in medium alone (35 vs 0%, respectively); however, development to blastoc ysts of 1- to 2-cell embryos cocultured with UTEC WaS less (P < 0.025) than that of 4- to 8-cell embryos cocultured with UTEC (35 vs 89%, re spectively).