HLA-G5 is present in erythroid and endothelial cells from a 16-day embryo. (A) Hematoxylin Eosin-Safran (HES) coloration of a paraffin-embedded 16-day embryo section (left) localizes the region of the YS for which higher magnifications of the same YS region stained with antibodies to CD34, HLA-G5, CD45, and CD71 are represented (right panel). Visceral endoderm and mesoderm are identified by VE and M, respectively, in the CD34 box. (B) The top boxed area is the chorionic plate (left) for which higher magnifications of the same region stained with antibodies to HLA-G5 and CD34 are represented (top right panel). The bottom area is the closed mesoderm (YS) (left) for which higher magnifications of the same region stained with antibodies to HLA-G5 and CD34 are represented (bottom right panel). In both localizations, HLA-G5 stains the CD34-positive endothelial cells. In both A and B, left panels are shown at × 100, and right panels at × 400.