[The interrelationships of the coccidian Cryptosporidium parvum (Apicomplexa: Sporozoa) with the cells of the immune system in the mammalian host].

By means of an electron microscopic study of the intestine in young rats infected with Cryptosporidium parvum we observed a mass migration of immunocompetent cells of the host (eosinophils, neutrophils and macrophages) into the lumen of intestine. Some lymphocytes were also observed. Immunocompetent cells (except lymphocytes) included inside phagosomes with different endogenic states of C. parvum. Macrophages with typical extracytoplasmic parasitophorous vacuoles formed by C. parvum were also observed in the intestine lumen. Almost all stages of C. parvum could be observed on a surface of such macrophages. However, we did not find in lamina propria of intestine villi any macrophages with parasites. The place of macrophages infection is unknown. We suggest that surviving of C. parvum in macrophages is principally possible.