Ultrastructural specialization of intestinal epithelium over Peyer's patches in the bonnet monkey, Macaca radiata.

The follicle associated epithelium (FAE) which separates the lymphoid follicle of Peyer's patch from the gut lumen is known to have specialized cells called M cells or "microfold" cells in man and certain animals. These cells are considered to be involved in antigen uptake and transport. Our light microscopic study of the small intestine of bonnet monkeys suggested the presence of such specialised cells in FAE. We have confirmed the presence of M cells in bonnet monkey FAE having ultrastructural features very similar to those of human M cells.

Microscopic anatomy of small intestine of Macaca radiata with special reference to gut associated lymphoid tissue.

The hitherto unreported microscopic anatomy of the small intestine of the bonnet monkey (M. radiata) was studied. There was a striking similarity in the general structure and cellular composition of the small intestine of the animal and that of humans. Of special interest was our observation of the occurrence of cells interspersed in the follicle associated epithelium which were morphologically similar to human M cells. These cells were pale, devoid of a brush border and frequently had lymphocytes apparently enclosed within them.