Growth and cell cycle defects without increased apoptosis in Cert^gt/gt mutant embryos. (A) Pregnant mice were injected with BrdU 1 h before dissection, and E10.5 embryos were dissected, genotyped, and stained for BrdU uptake as described in Materials and methods. Four of the areas chosen for counting the fraction of dividing cells are shown in the panels to the right. (B) Cert^gt/gt embryos showed a lower fraction of BrdU-positive cells, indicating a slower rate of cell division in these mutant embryos. Error bars indicate standard deviation; n = 4. (C) Western blot analysis for some of the components of the cell cycle in Cert^+/+ (+/+) and Cert^gt/gt (−/−) embryos. (D) Phosphorylated Akt levels are decreased in Cert^gt/gt embryos. (E) TUNEL staining of E10.5 wild-type and mutant embryos. Insets show boxed areas at higher magnification. There were no significant differences in the proportion of dying cells between the wild-type and mutant embryos. Note that the wild-type embryos are large compared with the mutant and, therefore, were photographed twice to include the upper and the lower halves of the embryo. The composites are shown in A and E.