Anoctamin 1 and c-Kit immunohistochemical study of interstitial cells of Cajal in the muscularis externa of human gastrointestinal tract

Background: Interstitial cells of Cajal (ICC) are widely distributed in human gastrointestinal (GI) tract, especially in the layer of muscularis externa between neurons and smooth muscles. They play a very important role of coordination of GI tract motility. The aims of this research were to study the morphology and distribution of ICC in the muscularis externa of the GI tract, using immunohistochemistry staining methods, to determine the distribution of immune reactivity of anoctamin 1 (Ano1) compared with c-Kit, and to determine if Ano1 is a reliable marker for ICC in human GI tract.Materials and methods: Specimens from the wall of stomach, small intestine, and colon were taken from human cadavers and processed for histological and immunohistochemical study using c-Kit and Ano1 primary antibodies.Results: Interstitial cells of Cajal appeared as bipolar cells, not forming network, in both the circular and longitudinal muscle layers, while in the myenteric area they appeared as multipolar interconnected cells. They were unevenly distributed in and between the muscle layers of the muscularis externa of human GI tract. They were more numerous in the stomach followed by the colon then the small intestine, and more numerous in the myenteric area followed by the circular muscle layer then the longitudinal muscle layer, in the three organs. Our results also showed that Ano1 is a more reliable marker for human ICC than c-Kit.Conclusions: Interstitial cells of Cajal differed in morphology and were unevenly distributed between muscle layers of muscularis externa and between different parts of human GI tract