FIG. 3.
Abnormal composition of the capillary BMs. Immunostaining of sections through muscles of the lower back of newborn Lama4+/+ and Lama4−/− mice. Blood vessels were visualized with an antibody to the endothelium-specific protein PECAM-1 (A and B). Arrows indicate examples of cross-sectioned capillaries. The staining intensity in blood vessels of the mutants was drastically reduced with antibodies against type IV collagen (C and D). Similar results were obtained with antibodies to nidogen (E and F) and to the laminin β1 chain (G and H). Note that anti-type IV collagen, anti-nidogen, and anti-laminin-β1 antibodies all readily stained BMs surrounding individual muscle fibers of Lama4−/− mice and BMs of blood vessels of Lama4+/+ mice. In contrast, perlecan could be seen in both capillary and muscle BMs in both −/− and +/+ mice (I and J). The laminin α4 chain is present around capillaries in the control mice (K), but it is totally absent in the mutant mice (L). Bar, 50 μm.