Abnormal FN deposition around mouse CCM1 or CCM2 lesions and ICAP-1–deficient blood vessels. (A) Sections of iCCM2 were labeled with total FN, cFN, and PECAM. CCM lesions are annotated by asterisks and normal blood vessels by arrows. cFN was abundant around CCM lesions, but barely detectable around peri-lesion blood vessels. Bar, 50 µm. (B and C) Numerous FN fibers appeared around the lesions (B, arrow), whereas FN signal was weak and diffuse around unaffected peri-lesion vessels (B, asterisk) or CT blood vessels (D). Strong collagen III staining was detected around CCM lesions but not around unaffected peri-lesion vessels or CT blood vessels. n = 3 mice for iCCM1, n = 6 mice for iCCM2. Bars, 10 µm. (E) Projections of confocal z-stacks of whole-mount of ear blood vessels of ICAP-1 +/+ and −/− mice immunostained for PECAM and FN. Blood had been washed out by intracardiac perfusion of PBS. The plot of intensity of the FN signal over the surface delineated by the yellow square is presented in the middle. Increased FN deposition as a mixture of soluble and thin fibrils around ICAP-1−/− blood vessels differed from the discrete FN fibers around ICAP-1+/+ blood vessels. n = 3 from two litters for each genotype. Bars, 10 µm.