Subunit b of cholera toxin labels interstitial cells of Cajal in the gut of rat and mouse.

Cholera toxin subunit b was found in vivo and in vitro to label interstitial cells of Cajal in the intestine of rat and mouse. Cholera toxin-labelled interstitial cells were present in the subserosa, the myenteric plexus and the deep muscular plexus of mouse small intestine, and the deep muscular plexus only of the rat small intestine. In the large intestine of the mouse, interstitial cells were present in the subserosa and in a plexus associated with the inner surface of the circular muscle, while in the rat they were only present in the latter location. Macrophages, which were present in many of the same locations as interstitial cells, were also labelled by cholera toxin but could be distinguished from interstitial cells by their ability to take-up fluorescein isothiocyanate-labelled dextran. Labelling with subunit b of cholera toxin is a simple way of labelling interstitial cells of Cajal and which is compatible with a range of physiological and histological procedures.