The male parasites die after copulation, while the females penetrate the crypts of Lieberkuhn, enter the submucosal lymphatics and deposit large numbers of larvae within the lymphatic spaces. These larvae migrate into the blood vessels and reach the striated muscles via the blood stream. They invade muscle bundles, where they become encysted and stay throughout the life of the host. In this case, the larvae occurred in many striated muscles, including the humeral and femoral musculature, the diaphragm, and the masticatory muscles, while the cardiac muscle was not affected. Identification of parasites in tissue sections requires detailed knowledge of the microanatomy of the various parasite groups.
Nematodes have a cuticle, musculature, pseudocoelom and gastrointestinal tract.
Key anatomic features of aphasmids are the presence of bacillary bands and stichosomes. In the United States, trichinosis was maintained in swine through the practice of garbage feeding. The institution of garbage cooking in the mid-1950's, as part of the vesicular exanthema eradication program, greatly reduced the incidence of the disease in the United States. Jubb KVF, Kennedy PC, Palmer N, 4th ed., pp. Veterinary Pathology, 6th ed., p. 629.