The morphology of Trichinella spiralis: ultrastructural study of the mid- and hindgut of the muscle larvae.

The ultrastructure of the gut of Trichinella spiralis muscle larvae is comprehensively described, based on extensive observations. The mid-gut was composed of a single cell layer of epithelium over the basal lamina, the brush border, the septate junction, prominent glycogen aggregates, and other common cell organelles. The epithelial cells of the midgut were basically uniform, but the lumen presented a remarkably diversified appearance. In the ampullar portion, the midgut accommodated an amorphous substance of medium electron density, the middle portion was collapsed, and the terminal portion again dilated, but without any particular contents. The mid- and hindgut were devoid of muscle cells that could be responsible for the peristaltic movement of the gut.