An ultrastructural study of the effect of neomycin on the colon in the human subject and in the conventional and the germ-free mouse.

An electron microscopic study of the colon of normal mice and human subjects and those treated with neomycin is reported; there is a close resemblance between the mouse and human colons. After rapid disinfection of the colon, there is epithelial cell damage due to a toxic effect of the drug, a reduction in epithelial turnover accompanying the change in flora, and an important reduction in the cellularity of the lamina propria mainly due to a reduction in inflammatory cells. The changes in the lamina propria probably represent changes in the antipathogenetic defences of the host.