Genetic Variation in the Timing of First Cleavage in Mice: Effect of Maternal Genotype

Abstract

Eggs from

Cytochrome P-450 metabolic activity in embryonic and extraembryonic tissue lineages of mouse embryos.

“…The SCE assay detects DNA lesions incurred before or during the first and second S phases after addition of BrdUrd. Morulae would complete their second S phase 2-3 hr before the end of culture (i.e, the length of G2) (21) (23,24).…”

Analyses of Developmental Ability of (BALB/c*C57BL/6) F1 and ICR Mouse Embryos Fertilized In Vitro and Their Chromosome at the First Cleavage Division.

“…The marked strain difference was obtained in susceptibility to the "2-cell block", a phenomenon in which embryos cultured in vitro arrest development at the late 2-cell stage. Embryos from most of the randomly bred strains of mice are susceptible to the block, whereas those of certain inbred strains and F1 hybrids between them are insusceptible and can develop to blastocysts in vitro [1,2,3,4]. The incidence of blocking was shown to be determined only by the egg genotype [5,6].…”

“…Concerning the genotype responsible for the strain difference in the timing of the cleavage division, 2 possibilities must be considered. Some investigators believe that it is the sperm genotype [3,29] and others that it is the egg genotype [4,8]. The occurrence of a "2-cell block" in certain strains of mice is known to depend on the egg genotype [5,6].…”

Analysis of Permissive and Repressive Chromatin Markers in In Vitro Fertilized Bovine Embryos Just After Embryonic Genome Activation

“…Furthermore, developmental block during embryonic genome activation (EGA) is not a common phenomenon for most mouse embryos, occurring normally to only some inbreed mice strains (Shire & Whitten, 1980). On the contrary, one of the main causes of embryonic arrest for bovine embryos appears to be the inability to overcome chromatin repression before maternal RNAs stock has been depleted, which occurs approximately by the 8cell stage (Meirelles et al, 2004).…”