Fig. 7. Reduced microvessel density, increased microvessel diameter, microhemorrhage and focal astrogliosis in adult endothelium-specific Pdgfb knockouts. (A-D) Double staining for ß-gal-positive PC nuclei (blue) and PECAM1 (brown) in the striatum (A,B) and cerebellum (C,D) of 3-week-old control (flox/flox; A,C) and lox/– (B,D) mice. Note the reduced number of PCs associated with the microvessels in the lox/– brain and the numerous pathological microvascular profiles seen in areas of complete PC loss (B, arrows). Remaining PCs in lox/– striatum correlate with more normal profiles, as judged by their even diameter and straight outline (B, arrowheads). A dramatic reduction of microvascular density is seen in lox/– cerebellum (D). Microhemorrhage, visible by macroscopic inspection in vibratome sections of P12 mice (E), was analyzed further by confocal microscopy using isolectin B4 coupled to FITC (green) and anti-GFAP antibodies coupled to rhodamin (red). The regions around the microhemorrhages (G,H; H represents the boxed region in G at higher magnification) showed strong GFAP expression in reactive astrocytes (arrows), as well as isolectin B4 staining of microglia (arrowheads). Regions in the lox/– brain without signs of microhemorrhage lacked signs of reactive gliosis (F). pl, pial surface; wm, white matter. Scale bars in A,C: 100 µm.