Hyaloid vessels from Sema6A^−/− mice and wild-type littermates. (A) Isolated hyaloid vessels from 4-day-old (P4) Sema6A-null and wild-type littermates were immunostained for Sema6A. Nuclei are visualized with DAPI. Representative images. (B) Morphology of hyaloid vessels isolated from P4 wild-type and Sema6A-null littermates; magnification of wild-type and Sema6A-null hyaloid vessels from corresponding areas outlined in the top panels. Representative images. (C) Number of branching points in hyaloid vessels isolated from wild-type and Sema6A-null littermates (n = 3, paired littermates; SEM; p reflects the statistical significance of group difference. (D) Protein extracts of isolated hyaloid vessels from wild-type (+/+), Sema6A heterozygote (+/−) and Sema6A-null (−/−) P5 mice were tested for VEGFR2 and β-actin by immunoblotting. Normalized (VEGFR2/β-actin) band intensity values are shown. (E) Isolated hyaloid vessels from P5 wild-type and Sema6A-null mice were immunostained for cleaved caspase 3 and Sema6A. Nuclei are visualized with DAPI. Comparable hyaloid vessel areas are magnified in the middle and right panels. Images on the right panels are from DIC (differential interference contrast microscopy).