Scanning electron microscopy of the cat small intestine and mucosal alteration observed duringToxoplasma gondiiinfection

THE small intestine of specific pathogen free (SPF) cats, some of which had been infected with Toxoplasma gondii, is described. In control cats the villi were long, and mostly leaf-shaped with a few finger-shaped villi. The villi showed several ridges and goblet cell openings on their surfaces. At high magnifications individual enterocytes were sometimes observed, dome-shaped with a hexagonal outline. Spaces between microvilli were resolvable on swollen cells lying near the apical extrusion zone of villi. Villi in infected cats had a similar morphology but were often shortened. Enterocytes which contained parasites were often so enlarged that the spaces between microvilli were easily resolvable. Apertures on the villus surface were seen, caused by the escape of parasites from the enterocytes. Oocysts and merozoites were seen in infected cats.