Whole-mount in situ hybridization analysis.Plvap mRNA expression in WT and Flk1 KO embryos isolated at 8.5 dpc (A). WT embryo at 7.5 dpc (B), 8.5 dpc (C), 9.5 dpc (D), and 10.5 dpc (E) Scale bar indicates 100 μm. Ex indicates extraembryonic region; and em, embryonic region. (F) Transverse section of embryo 8.5 dpc. (G) Enlarged image of region indicated by rectangular box in panel F. DA indicates dorsal aorta; and NT, neural tube. (H) Enlarged image of region indicated by rectangular box in panel F. HC indicates primitive hematopoietic cells; and VE, visceral endoderm. (I-J) Arap3 at 8.5 and 9.5 dpc, respectively. (K-L) Gpr182 at 8.5 and 9.5 dpc, respectively. (M) Strong expression of Gpr182 in the yolk sac at 8.5 dpc. (N) Gpr116 at 9.5 dpc. (O-Q) Tmem204 at 8.5 dpc (O) and 9.5 dpc (P). High magnification images of intersomitic vessels (Q) of embryo at 9.5 dpc. (R) Lateral view of Arhgef15 at 9.5 dpc. Images (A-R) were captured with a Leica DC500 CCD camera attached to a Leica MZ FLIII microscope (Plan APO 1.0/0.125 NA lens) and with IM50 Imaging Manager.