THE FINE STRUCTURE OF THE SOMATIC MUSCLE CELLS OF THE NEMATODE CAPILLARIA HEPATICA (BANCROFT, 1893)

Abstract

The fine structure of the somatic muscle cells of the parasitic nematode Capillaria hepatica (Bancroft, 1893) has been examined using both electron microscopy and light-microscope histochemistry. The general cell architecture conforms to that of coelomyarian muscle cells as known from earlier lightmicroscope studies of other nematodes, except in the identity of the contractile elements of the cell. Myofilaments, approximately 250 Å in diameter, are located throughout the contractile region of the cell. These myofilaments may follow helical paths within the sarcoplasm. The significance of dense, lipoprotein thickenings which occur along the inner surface of the cell membrane of the contractile region, and of flattened, sac-like membrane units which lie close to the cell membrane of this region, is as yet unknown. Glycogen occupies most of the cell body of the muscle cell, while mitochondria, endoplasmic reticulum, and Golgi zones are located in the peripheral and perinuclear cytoplasm. The sarcolemma consists of the cell membrane and an extracellular layer of material closely associated with it. This extracellular component of the sarcolemma is thickest around the contractile region of the cell. The muscle cells are underlaid by a basement membrane continuous with that under the cells of the hypodermal cords.