Fig. 4. Abnormal vasculogenesis in Man1^GT/GT embryos. (A-C) Whole-mount views of wild-type (+/+, left) and Man1^GT/GT (right) yolk sacs. (A) A blood pool formed in the mutant yolk sac at E10.5 instead of the distinct blood vessels in the wild-type at E9.5. (B) Benzidine staining at E9.5 indicates formation of hematopoietic cells within the blood vessels. (C) Whole-mount immunohistochemistry staining at E9.5 with a PECAM-1 antibody labels endothelial cells in the blood vessels. (D-F) Whole-mount immunohistochemistry in the embryo proper at E9.5 with a blood vessel marker, FLK-1. Arrows indicate a well-formed vasculature in the wild-type (D) and disorganized vasculature (E) and dorsal aorta (F) in the Man1^GT/GT. (E,F) Man1^GT/GT embryos appeared to be developmentally delayed by 24-36 hours. bp, blood pool; ht, heart; nf, neural fold; ve, blood vessels; ys, yolk sac. Scale bars: 1 mm.