THE DEVELOPMENT OF LYSOSOMES IN RAT SKELETAL MUSCLE IN TRICHINOUS MYOSITIS

Rat striated muscle (gastroenemius) containing encysted Trichinella larvae was studied histochemically for hydrolases associated with lysosomes. Activity of the enzymes studied (acid phosphatase, esterase, aminopeptidase), not demonstrable in appreciable amounts in normal striated muscle, appears in the altered muscle fibers in granules which by various criteria are demonstrated to be lysosomes. The increase in lysosomal enzyme activity is accompanied by increased prominence of the Golgi apparatus, as demonstrated by thiamine pyrophosphatase activity, and by an increase in the ribonucleoprotein content of the muscle fibers. These changes illustrate the facultative development of lysosomes and their associated ferments during a regenerative process. They suggest the need for a revision of the classic concept of the primarily degenerative nature of the trichinous lesion as well as a possible role of the developing lysosomes in this process.