Pericyte-endothelial cell ratios were determined by isolation of capillaries [2-4 micron diameter determined by Image J software] from wild type B6 mice (A); heterozygous GFAP -/+ mice (B) and knockout GFAP -/- mice (C). Freshly isolated capillaries were stained with the fluorescent nuclear dye 4',6-diamidino-2-phenylindole [DAPI]. Round nuclei (pericytes) and elongated nuclei (EC) were counted. Numbers are shown in Table 1. Arrows point to round pericyte nuclei.