(A) Schematic diagram of the Mr5 transgene. (B,C) Frozen sections of small intestine from newborn Het/Tg (B) and KO/Tg (C) mice. Immunostaining for laminin α5 revealed similar levels in the epithelial (inner) BM. (D-I) Representative pictures of laminin α5 staining in the proximal (PSI), middle (MSI) and distal (DSI) small intestine of adult mice. (D,F,H) Laminin α5 was abundantly deposited in the subepithelial BM of control villi (denoted by arrowhead), with almost none in the crypts. (E,G,I) Laminin α5 was greatly reduced in the villus BM of KO/Tg mice but was detectable in mesenchymal structures within villi (arrows) and in intestinal smooth muscle (asterisk) of both Het/Tg and KO/Tg mice. Bars, 100 μm.