Skeletal muscle fibre ends of the frog as revealed by scanning electron microscopy.
Muscle fibre ends at myotendinous junctions were examined by scanning electron microscopy after removal of tendon connective tissues by HCl-hydrolysis in the fourth extensor digitorum longus muscle and the extraocular muscle of the frog. The fibre ends in both muscles were characterized by the presence of small pit-like and short slit-like invaginations. The fibre ends in the extensor digitorum longus muscle took a spongy appearance with a great number of invaginations, while those on the extraocular muscle consisted of a number of pits and short slits arranged linearly toward the fibre tip. These findings confirm that muscle fibre ends in the frog consist of sarcolemmal invaginations to increase the surface area where collagen fibrils attach to the basal laminae of muscle fibres. The difference of the surface specializations between two kinds of muscle fibres may intimately reflect the functional properties of the muscle.
Desaki
J
J
Department of Anatomy, Ehime University School of Medicine, Japan.
D000818:Animals; D005123:Eye; D008855:Microscopy, Electron, Scanning / Q000379:methods; D018485:Muscle Fibers, Skeletal / Q000648:ultrastructure*; D018482:Muscle, Skeletal / Q000648:ultrastructure*; D011898:Ranidae; D014034:Toes