Immunohistochemical identification of the pacemaker cajal cells in normal human colon

ABSTRACT

The Interstitial Cells of Cajal [ICC] are C-Kit immunoreactive cells in the gastrointestinal tract. They are suggested to have a role in the control of gut motility. The present study was aimed to identify the morphology and the pattern of distribution of the ICC in the different parts of the human colonic segments. This study included sixteen normal colonic specimens obtained from the safety margins of the surgically excised colonic carcinoma. The prepared colonic longitudinal sections -were subjected to haematoxylin and eosin, Masson's trichrome stain and to C-Kit immunohistochemistry. Statistical analysis was performed on the obtained data through the use of Leica Owin software of the image analyzer computer system to evaluate the degrees of locations of ICC [area percent] in the different colonic segments. The results revealed the following ICC were demonstrated either as groups or as sporadic cells. The groups of ICC were surrounded with concentric connective tissue cells. The sporadic cells were usually in close relation to blood vessels and to the circular smooth muscle layers. ICC were of different sizes and different shapes. Statistical analysis through the use of the image analyzer was performed on the data obtained after examination of ten fields from each colonic segment. The area and area percent of the stained ICC were recorded in relation to a standard measuring frames. The obtained results revealed that great numbers of ICC were present at the coeco-colonic junction. The ascending, transverse and descending colonic segments showed moderate number of ICC. The greatest numbers of ICC were recorded in the region of sigmoid colon. ICC were located in the level of myenteric plexus, between the circular and longitudinal smooth muscle layers or within the circular muscle layer itself as reported in the sigmoid colon. The obtained results were discussed from the fact that ICC are considered to be generators of spontaneous pacemaker activity in the smooth muscle layers of the colon. They mediate or transduce inputs from enteric motor nerves to the smooth muscle syncytium