Pathological features are evident in Lama2-deficient mice within 7 days after birth. (A) Lama2-/- mice are of normal size at birth but are smaller than are Lama2-expressing siblings by 7 days of age. Body mass at 1 and 7 days of age is shown for wild-type Lama2+/+ (solid bars), Lama2+/- (shaded bars), and Lama2-/- (white bars) mice. The two age groups represent two separate cohorts of mice, n≥12 mice for each data point (see text). Data shown as mean ± SE, *p<0.002. (B) Tenascin-C (TN-C), a marker of inflammation, is dramatically upregulated in Lama2-/- quadriceps muscle at 7 days of age. Muscles immunostained for TN-C expression show deposition of TN-C in the endomysium surrounding muscle fibers in patches or foci within the muscle, including regions where loss of muscle integrity is not apparent morphologically. There is no TN-C in endomysium of wild-type muscle fibers at this age (scale bars=100 µm).