Intestinal mast cell changes in guinea pigs infected with the nematode Trichostrongylus colubriformis.

Infection of guinea pigs with the parasitic nematode Trichostrongylus colubriformis was followed by a three- to fourfold increase in the number of mast cells in the small intestine mucosa. Mitotic figures were observed in many mast cells during the period numbers were increasing. Many mast cells developed cytoplasmic granules which, unlike pre-infection mast cell granules, contained crystalline structures.