Immunohistochemical study of the c-kit expressing cells and connexin 43 in the guinea-pig digestive tract.

The distribution of the c-kit receptor expressing cells and gap junction protein, connexin (Cx) 43 in the guinea-pig stomach (antrum), small intestine (jejunum) and colon (ascending) was studied by immunohistochemistry. The anti-c-kit protein immunopositive cells were regularly observed in the myenteric region throughout all three organs. The immunopositive cells were also sparsely distributed in the circular muscle layer of both the stomach and the colon, but not in the small intestine. They were densely located in the regions of the deep muscular plexus (DMP) of the small intestine and submuscular plexus (SMP) of the colon. In contrast, strong immunoreactivity to anti-Cx 43 antibody was observed in almost the entire thickness of the circular muscle layer of the stomach and the small intestine, but not in the colon. Dense immunoreaction deposits were observed in the region of the DMP and SMP. However, only very weak immunoreactivity to anti-Cx 43 antibody was detected in the myenteric region of all three organs. These results suggest that the c-kit receptor expressing cells or interstitial cells of Cajal (ICC) in the myenteric region of the three organs, and in the SMP of the colon, are poorly coupled with the bulk of circular muscle tissue by gap junctions, while ICC in the DMP and in the circular muscle layer of the stomach couple well with the surrounding muscle tissue.