title: In vitro analysis of pre- and early postimplantation development of lethal yellow (Ay/Ay) mouse embryos.
abstract: Preimplantation embryos from matings between yellow heterozygous (Ay/a) mice were recovered at 56 hours post coitum, cultured for five days, and compared with the development of embryos from three control matings (Ay/a female X a/a male, a/a female X Ay/a male, a/a female X 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 less than 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 are 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.
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology; D003433:Crosses, Genetic; D047108:Embryonic Development; D005260:Female; D005804:Genes, Lethal; D006579:Heterozygote; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains / Q000196:embryology*; D011247:Pregnancy