Arrangement and identification of proteoglycans in basement membrane and intramuscular connective tissue of bovine semitendinosus muscle.

The arrangement and identification of PGs in the basement membrane and intra-muscular connective tissues of bovine semitendinosus muscle were studied electron-microscopically using cuprolinic blue, a cationic dye, to detect PGs. Three different types of PGs were observed in bovine semitendinosus muscle: The first, PGs of 20-40 nm in length, were arranged along the lamina lucida below the cell membrane. The second, PGs of 50-70 nm in length, were arranged randomly on the outer surface of the lamina densa. The third, PGs of 40-60 nm in length, were associated with collagen fibrils at regular intervals in the endomysium and perimysium. Cytochemical analysis using various GAG-degrading enzymes showed that PGs in the basement membrane were predominantly heparan sulfate PGs, and those associated with collagen fibrils in the perimysium were rich in chondroitin or dermatan sulfate, or both.