Identification of interstitial cells of Cajal in the human rectum.

It is postulated that the electric waves of the gut are generated by interstitial cells of Cajal (ICC). We hypothesized the presence of ICC in the rectum as initiating the rectal electric activity. The current study investigated this hypothesis. Two rectal specimens were taken from healthy areas of excised rectum of 22 rectal cancer patients (age 44.6+/-.2 SD years, 12 men, 10 women). The study specimens were subjected to c-kit immunohistochemistry. Controls for antisera specificity consisted of tissue incubation with normal rabbit serum substituted for the primary antiserum. C-kit positive branched ICC-like cells were detected in the rectal musculature of the studied specimens. They were distinguishable from the c-kit-negative non-branched smooth muscle cells and from the c-kit positive but non-branched mast cells. Immunoreactivity was absent in the negative controls. We have identified in the rectum for the first time cells with morphologic and immunologic phenotypes similar to the ICC of the gut. The role of these cells in normal physiologic and pathologic conditions of the rectum needs further studies.