Establishment of equine oviduct cell monolayers for co-culture with early equine embryos.

A culture for equine oviduct epithelial cells is described. Primary cultures reached confluence in 5-8 days, forming a monolayer of polygonal cells and remaining morphologically intact for about 20 days. Subcultures were obtained by collecting cells detached spontaneously from the monolayers, and confluence was reached again after 5-7 days. Cells frozen before primary culture were confluent 10-15 days after thawing. Dishes containing confluent cells also were frozen, and some cohesive monolayers formed after thawing. Equine embryos, collected 2 days after ovulation, were cultured alone or with a monolayer of equine oviduct epithelial cells. Of 5 embryos cultured alone, 3 contained 12-20 cells, 1 was at the morula stage and 1 reached the blastocyst stage after 4 days. Of 5 embryos co-cultured with oviduct cells, 2 contained 12-16 cells, 1 was at the morula stage and 2 reached the blastocyst stage after 4 days. After 2 more days, the blastocysts showed only delayed development; there was no capsule, and limited increase in size. Equine embryos can develop in vitro from 4-8 cells to the blastocyst stage, in co-culture with equine oviductal monolayers and also without cellular support. The number of embryos studied was too small for us to draw conclusions about the benefits of co-culture.