Fig. 5. Expression of endothelial and smooth muscle cell markers in the yolk sacs of Man1^GT/GT embryos. (A) H&E staining of paraffin sections of wild-type (+/+) and Man1^GT/GT yolk sacs (GT/GT). (B) Immunohistochemistry for PECAM-1 reveals disorganized morphology of endothelial cells. Embryos were stained in whole mount followed by paraffin sectioning. (C) Immunohistochemistry for FLK-1 showing vascular cell disorganization in the mutant. (D) -smooth muscle actin staining shows a reduction in smooth muscle cells in the mutant. (E) Immunofluorescence staining for fibronectin, showing an apparent increase in signal in the mesoderm of the mutant with a reduction of expression in the endoderm. am, amnion; bc, blood cells; ec, endothelial cells; me, mesothelium; ve, visceral endoderm. Scale bar: 50 µm.