Investigations into the location of Treponema hyodysenteriae in the cecum of experimentally infected young broiler chicks by light- and electronmicroscopy.

Numerous Treponema hyodysenteriae were present both on the mucosal surface and in the deep crypts of the cecum of young broiler chicks 7 and 14 days after inoculation with the treponemes. The treponemes in the ceca of chicks inoculated with 10(8) cells were observed more frequently than those of chicks inoculated with 10(7) cells. The treponemes in the ceca were observed by light microscopy, scanning electron microscopy and transmission electron microscopy. The lesions were primarily confined to the cecum. Desquamation of epithelial cells, edema, leukocytic infiltration and hemorrhage were observed in the mucosae.