Trichinella spiralis: an intracellular parasite in the intestinal phase.

Trichinella spiralis has been examined by electron microscopy after fixation in situ in the intestine of mice. The worms lie within the cytoplasm of cells of the intestinal mucosa and may occupy both absorptive and goblet cells. They cause little damage to host cells. A few worms have been seen protruding from tissue by SEM techniques. These unusual observations suggest that the nematodes may be capable of exit and reentry into the epithelium.