Two-cell embryos were recovered from ICR, Balb/c, and Fl hybrid (CBA X
C57Bl/6) females, and cultured in vitro in the Ham's F-I0 medium supplemented with 0.1
% BSA, 20 mM Na-lactate, or 10 mM HEPES. With Fl hybrid embryos, there were significantly
higher development in Ham's F-I0 medium supplemented with 0.1% BSA (79.1%)
and lower development in that supplemented with 10 mM HEPES. Significant differences
between strains were seen also, and preimplantation deveiopment was significantly better
with the embryos of the Flhybrid strain and was lower with the embryos of the Balb/c strain.
It was concluded that BSA and Na-lactate are the important factors affecting preimplantation
development, and embryos of the Fl hybrid strain are less sensitive to culture conditions.
After transplantation of blastocysts cultured in vitro, the pregnancy rate of recipient mice
and implantation rate of transferred embryos were 60% and 32%, respectively