Fig. 4. Hhex^–/– embryos have defective angiogenesis. (A,D) Low-power view of whole E11.5 Hhex^+/+ and Hhex^–/– embryos stained with Pecam antibody. Hhex^–/– embryos have a striking profusion of small vessels and disorganization of large vasculature throughout the whole embryo. (B,E) High-power view of cranial vascular detected with PECAM antibody. Note the disorganization of large vessels and the multiple ectopic small vessels that are present. Visualization of various focal planes indicates that the punctate staining represents small vessels branching off the larger vessels that are not in the plane of focus. Arrows indicate the same cranial vessel in each embryo for comparison. (C,F) The intersomitic vessels are also enlarged and have abnormal small branches (arrowheads).