An electron microscope study of the ring fibers and its neuromuscular junction in human progressive muscle dystrophy.

It is known that ring fibers are often observed in some human muscle diseases, especially in myotonic dystrophy (HEIDENHAIN, 1918; PERRY et al., 1956; SCHOTLAND et al., 1966), and in normal ocular muscles (WOHLFART, 1932; MORI, 1953; RUBINSTEIN, 1960; BETHLEM and VAN WIJNGAARDEN, 1963; INKE and SITKA, 1965 and others). Although there have been a few reports dealing with the fine structure of these ring fibers (SCHOTLAND et al., 1966), very little is known about the stuructural details of their neuromuscular junction. The present paper describes the fine structure of the ring fiber and its neuromuscular junction in human muscle disease.