Blastomere content of cultured/frozen bovine demiembryos.

The purpose of the study was to evaluate whether a period of co-culture with bovine oviduct epithelial cells (BOEC) could improve the tolerance of bisected bovine embryos to freezing and thawing. Day 6 embryos were bisected and the resulting demiembryos were stained with Hoechst 33342 and cell counts were made by counting intact blastomere nuclei. Of these, 11 were stained as freshly manufactured demiembryos, 25 after co-culture for 24 h with BOEC and 37 stained after 24 h co-culture and freezing and thawing. The staining revealed, that there was no significant difference in cell count of demiembryos that were stained immediately after bisection, compared to those, that were co-cultured for a 24 h period. Also, the co-cultured/frozen/thawed demiembryos had a significant decrease in cell numbers compared to the non-frozen demiembryos. We conclude, that a 24 h period of co-culture with BOEC does not result in appreciable cellular proliferation in demiembryos and therefore instead of improving the survival of frozen/thawed demiembryos by giving them opportunity to multiply their cell number and thus make them more resistant to cell damage, rather compromised the viability of cryopreserved demiembryos.