Enteric serosal surface in the piglet. A scanning and transmission electron microscopic study of the mesothelium.

The ultrastructure of the serosal mesothelium of the stomach, and small and large intestine has been investigated for the first time by scanning and transmission electron microscopy in the normal piglet. Its fine structure is similar to that reported previously for the calf and rat visceral mesothelium and is notable for the presence of abundant, long, widely spaced microvilli extending from the apical surface of mesothelial cells. Large rough endoplasmic reticula, free ribosomes, and pinocytotic vesicles were numerous, but Golgi apparatuses, mitochondria, lysosomes, and other intracellular inclusions were scarce. Little difference was observed between the serosal mesothelium of the three regions investigated. This information on the normal piglet mesothelium may be useful for future studies of pathogenesis of experimentally induced peritoneal adhesions, since the immature animal is at elevated risk and the porcine digestive tract resembles that of the human.