Techniques of preparation (distension, washing, fixation, dehydration, etc.) of the intestinal mucosa for study with the scanning electron microscope (SEM) have been described. The villi vary in appearance depending upon the individual, the genus, the region of the gut from which they are obtained, their physiological state of activity as well as the techniques used in their preparation. The most
... [Show full abstract] striking features of these structures are the various ways in which the total absorptive and digestive surface areas are increased within a limited space. These include the abundance and topographical arrangement of the villi, their size and shape, the fissures characteristic of their surfaces as well as the number of microvilli present per unit area on the apical surface of columnar epithelial cells. Species variations of all these are described. The number of villi per unit area, the number of crypt orifices surrounding a single villus, and the number of microvilli per unit area have been counted in the species studied. A three dimensional view of the relationship of villi to intervillus floor, crypt tubule pores and crypt tubules has been described. The SEM provides better three dimensional views of the mucosa than is possible with other available instruments.