Fig. S2.

The E9.5 PE holds an intrinsic vascular potential. (A) Semiquantitative RT-PCRs confirm that E9.5 PE cells express vascular progenitor (Scl/Tal1/Vegfr-2) and endothelial (CD31) markers. (B and C) Low CD31 expression in PE is in accordance with the accumulation of differentiated CD31⁺ CoE cells in the dorsal aspect of the PE (arrowheads in B and C; the whole PE is marked by a dotted line in C). (D–F) In vitro-cultured E9.5 PE differentiate into CD31⁺ CoE cells only in the presence of VEGF (compare E and F with D). (Scale bars: 100 µm.)