An ultrastructural study of the interstitial cells of Cajal of the human stomach.

The interstitial cells of Cajal of the human stomach were studied at the electron microscope. These cells have an exceptionally elongated shape and several lateral branches. Their cytoplasm characteristically possesses cisternae of smooth endoplasmic reticulum and filaments. A capsular-like structure surrounds them and joins them to each other and to the neighbouring nerve endings and smooth muscle cells, and so they all make up anatomical units. Elastic fibres also make bridges between these cells and between smooth muscle cells and nerve endings. Despite these common characteristics, differences in cell number, distribution in respect of the muscle bundles and some cytoplasmic features have been found, depending on where these cells are located. In fact, there are few interstitial cells in the fundus, poor in filaments and branches, and only located inside the circular muscle layer. In the corpus and antrum they are many, rich in filaments and with their numerous branches make interconnected networks, one inside the circular muscle layer, another apposed to its myenteric surface and, in the antrum, a third one apposed to its submucosal surface, which accompany analogous nerve networks. Substantial differences in the contacts between the interstitial cells and the smooth muscle cells and nerve endings have not been found. For their ultrastructural characteristics a smooth muscle nature has been suggested for these cells. A correlation has also been attempted between the electrical and mechanical activities performed by the different gastric areas and the interstitial cell structure and arrangement.