Electron microscopic examination of basal lamina in Fukuyama congenital muscular dystrophy.

By light microscopy we previously obtained immunocytochemical evidence for basal lamina (BL) abnormality of skeletal muscle in Fukuyama congenital muscular dystrophy (FCMD). To further elucidate the pathological involvement of the BL in FCMD, we examined by electron microscopy the skeletal muscle in 12 cases of FCMD, nine cases of age-matched neuromuscular diseases unrelated to FCMD, and a case of merosin-negative CMD (MCMD). We found that the BL of skeletal muscle fibres in all patients with FCMD and the MCMD patient had a thin, deranged and often disrupted appearance. These features were more prominent in large calibre (> 15 microns) fibres than in small calibre (approximately 8 microns) fibres. Replication of the BL was not observed in 11 of the 12 FCMD patients. Although the BL over the intact plasma membrane had occasional gaps, the plasma membrane under the disrupted BL was normal in some case. Our results indicate the presence of fragile BL which may precede plasma membrane damage in FCMD skeletal muscle.