Table 1

In vitro embryo development

Number of embryos at various times after mating
0.5 day 1.5 days 2.5 days 3.5 days
Male(Egg harvest)1234M1234M1234M
wt(66 eggs)*273632631412112633232
Cre(60 eggs)*40191331674331674
  • Three wild-type (wt) and three heterozygous Prm1-Cre-hGH (Cre) males were mated with wild-type females (all males were 12–24 wk old, females were 6–8 wk old), and eggs were harvested from oviducts of sacrificed females on the following morning (0.5 day postmating). Zygotes were cultured for 3 days, and the number of 1-, 2-, 3-, 4-, and >4-celled (morulae and blastocysts) embryos (1–4 and M, respectively) were counted each day. 

  • * Some of the one-celled embryos may have been unfertilized eggs or may have been damaged during harvest, accounting for the embryos that did not progress beyond the one-celled stage in matings with either wild-type or Prm1-hGH-Cre males. Embryos harvested at 2.5 days after fertilization from matings with either wild-type or Prm1-Cre-hGH males contained only 10% one-celled embryos (see text), which is consistent with this interpretation.