Fig. 6. Abnormal brain capillary morphologies in class B integrin ß8-deficient mutants. (A-D) Paraffin wax embedded sections of E12.5 (A,B) and E14.5 (C,D) brains stained with anti-laminin antibodies that show the abnormal morphologies of capillary vessels in the integrin ß8-deficient mutant (B,D) when compared with a wild-type littermate (A,C). Discontinuous basement membranes are indicated by arrows (B). Aggregates of capillary vessels are visible (D, arrow). (E-F) Projected confocal images of E12.5 brain capillary vessels double labeled with anti-PECAM antibody (green) and anti-FN (red) antibodies. Capillary vessels in an integrin ß8-deficient mutant (F1-3) exhibit irregular distended morphologies and are often conjoined when compared with those in wild-type littermates (E1-3). The basement membrane is discontinuous and a blood cell is captured at a potential hemorrhage site (F2, arrow) in the mutant. Note that a blood cell is present clearly outside of the capillaries, indicating hemorrhage in a nearby location (F3, arrow). (G,H) Pericytes recognized with anti-desmin are present and recruited to the capillaries in the brains of E12.5 wild-type (G, arrow) and mutant embryos (H, arrow). Scale bars: 50 µm in A-D; 20 µm in E,F; 100 µm in G,H.