Figure 3.

Loss of Ln α4 does not otherwise affect endoneurial BL composition or structure. (a–a′) Medial sciatic nerve sections from adult (6–9 wk) wild-type (a–i), dy2J (j–r), and Lama4 ^−/− (s–a′) mice were stained with antibodies to the Ln β1 (a, j, and s), α1 (mAb 198; b, k, and t), α2 (c, l, and u), α4 (mAb 1G5: d, m, and v; polyclonal: e, n, and w), and α5 (f, o, and x) chains, and to entactin (g, p, and y), perlecan (h, q, and z), and agrin (i, r, and a′). Double-labeled sections show α4 (e1, n1) coconcentrated with α2 (e2) at ab-axonal surfaces (arrowheads) of Schwann cells (S100 in n2); axons are stained for neurofilaments (e3; arrow). Changes in dy2J include degraded staining for α2, variable up-regulation of α1, and uniform up-regulation of α4. Ln α4 deficiency does not alter distribution of other Lns or BL components. (b′–d′) Electron micrographs of endoneurial BLs (arrows) in mature control (b′), dy2J (c′), and Lama4 ^−/− nerves. BL integrity is disrupted by mutations in Ln α2 but not α4. Bar in a′, 30 μm in a–a′; 0.45 μm in b′–d′.