A combined electron microscopic investigation of the peritoneal mesothelium in the rat.

Visceral and parietal peritoneum of adult Wistar rats was studied by means of transmission and scanning electron microscopy. The structure of the peritoneum follows a general plan: mesothelium, basal lamina, and submesothelial connective tissue layer. Two basic types of mesothelial cells are described: flat and high (cubic), as well as transitional forms. A regularity of distribution of these cells in the visceral and parietal peritoneal sheets, and in the cover of individual organs and regions is described. A functional characterization of the different types of mesothelial cells is attempted, based on the differences of their cytoplasmic organization. The involvement of the mesothelium in the homeostasis in the peritoneal cavity is discussed.