Fig. 1. Deletion of the HoxA cluster leads to impaired vasculature in the placental labyrinth.

(A–D) Histology of wild-type (A) and HoxAdel/del mutant (B) mouse placentas at E10.5 as revealed by Hematoxylin and Eosin staining of paraffin sections. At high magnification, the mutant labyrinth (D) appears more compact than wild-type (C), which is likely to be a consequence of reduced fetal vasculature. (E–H) Whole-mount CD31 immunostaining of the vascular endothelium of wild-type (E) and mutant (F) hemi-placentas at E10.5. The boxed regions of E,F are magnified in G,H. In the wild-type placenta, the vasculature expands into the entire labyrinth (E,G). In the mutant (F,H), large labyrinth regions are deprived of vasculature and characterized by the absence of brown staining (H, black dashed lines delimit vasculature-deprived regions within the labyrinth). (I,J) Immunohistochemical analysis of CD31 expression on cryosections of wild-type (I) and mutant (J) placentas at E10.5 (n=11). Arrows point to the large regions deprived of endothelial cells in the mutant labyrinth. In all panels, white dashed lines mark the boundary between the labyrinthine region (lab) and the decidua (dec). Scale bars: 200 μm.