In situ hybridization for placental transcription factors. There are no obvious differences in the amount or localization of Hand1
(A–C), Ascl2
(D–F), or Gcm1
(G–I)-positive trophoblast cells in Cx31.1−/− placentas compared to controls. Ki67 staining (J, K) and quantification of Ki67-positive cells (L) reveal no differences in the number of proliferating cells in Cx31.1−/− placentas. TUNEL assay reveals only basal apoptosis levels (arrows) in Cx31.1−/−
(N, O), and control placentas (M). Scale bars represent 100 μm in A–I; 200 μm in J–O. Insets show higher magnification of stained areas. D, decidua; L, labyrinth; S, SPT; arrowheads, TGC.