Histological observations with respect to the immune mechanism in Eimeria acervulina infection in the domestic fowl.

Abstract

A strong repulsion of epithelial tissue into the intestinal lumen associated with a lowered intestinal pH, thin liquid intestinal contents and leakage of serumprotein into the lumen was observed in E. acervulina immunized birds, some hours following oral reinfection. The extruded epithelial tissue degenerated and died in the lumen; massive numbers of dying cells could also be observed in tissue sections of the intestinal contents. Most likely the sporozoites are pushed off together with the cells. The repulsion was always associated with a prominent swelling of the muscles in the intestinal villi. In the not immune birds however, some cell repulsion and a little swelling of the villous muscles was observed but only at the tips of the villi. In the normal not infected individual contraction of the villous muscles supports the physiological repulsion of epithelial cells at the so called “extrusion zone”.