Morphological Studies of the Mucous Membrane of the Small Intestine of Vertebrates with an Emphasis on Comparative Anatomy

In order to explicate the morphological and adaptive variations occurring in the mucous membrane of the small intestine, a morphological study was conducted from a phylogenetic viewpoint of the small intestinal mucosa of fish, amphibians, reptiles, birds and mammals, including man. A tendency for the mucosa to have gradually changed from that of folds only to that of fine villi as evolution proceeded was noted. It was further noted that as the evolutionary scale is climbed, there is a tendency for both the columnar cells, which make up the epithelium, and the microvilli observed at their apices to become shorter. Another interesting discovery was that the basal lamina of the mucosal epithelium of fish living near the delta of rivers is multi-layered and has a unique wavelike laminar structure

Morphological Study of Microfold Cells of Intestinal Lymphoid Follicles in Peyer\u27s Patches

A study was made of the morphology of microfold cells (M cells) of the human and rat Peyer\u27s patch, and the morphological changes occurring due to aging and disease were examined. In the mature rat, the microfolds were classified into four types, and the microfolds were found to differ according to age. A microfold jutting out as a long, thin projection was noted in a patient with an intestinal infection. There was a close relationship between the enclosure of lymphoid cells by M cells and age in that with increasing age there were more M cells with enclosed lymphoid cells as well as more lymphoid cells within one M cell. It was also shown that pinocytosis as described by Fawcett occurs along with micropinocytosis in the incorporation of macromolecules