In vitro analysis of pre implantation and early post implantation development of lethal yellow a y a y mouse embryos/
Johnson, L.L.; Granholm, N.H.
Journal of Experimental Zoology 204(3): 381-390
Preimplantation embryos from matings between yellow heterozygous (Ay/a) mice were recovered at 56 h post coitum, cultured for 5 days and compared with the development of embryos from 3 control matings (Ay/a.female. .times. a/a.male., a/a.female. .times. Ay/a.male., a/a.female. .times. a/a.male.). Most embryos were at the 8-cell stage at recovery; however, fewer embryos from the experimental cross had developed to the 8-cell stage than embryos of control matings, indicating a developmental lag of experimental embryos (P < 0.01). The yellow (Ay/a) uterus did not contribute (P = 0.05) to delayed development. Experimental and control embryos were equally capable of successful development in culture to the morula stage with no distinct morphological characteristics identifying the class of Ay/Ay mutants. However, significant differences were observed in the development from morulae to blastocysts; 9.4% (10/106) of the morulae in experimental crosses failed to undergo blastocyst formation as compared with 2.5% (10/398) of morulae in pooled control crosses (P = 0.010-0.025). In the experimental cross 25.0% (24/96) of embryos that developed successfully to the blastocyst stage failed to hatch from the zona pellucida; these were presumed to include the class of lethal yellow homozygotes. Abnormalities seen in cultured embryos consisted primarily of blastomere disintegration, blastomere arrest and exclusion and embryo fragmentation.