Interstitial cells of Cajal in the guinea pig gastric antrum: distribution and regional density.

Interstitial cells of Cajal (IC) have been described in the gastrointestinal (GI) tract of various species and functional studies have suggested that different classes of IC support key physiological roles in GI motility. IC express a specific cell surface tyrosine kinase receptor, c-kit. We have studied the distribution of IC in the gastric antrum of the guinea pig by immunohistochemistry using c-kit antibodies. We have identified four classes of IC on the basis of their anatomical location within the gastric wall. IC in the myenteric plexus region (IC-MY) formed a dense network; they were reduced in density at the lesser curvature compared to the greater curvature. Intramuscular IC (IC-IM) were found in the longitudinal and circular muscle layers in muscle bundles; the density of IC-IM in the circular muscle layer covaried with that of nitrergic myenteric neurons along the circumference of the antrum. Two other classes of IC are described for the first time. IC were found within septa (IC-S) that separated the circular layer into muscle bundles; IC-S were orientated perpendicular to the circular muscle from the myenteric to the submucosal region. IC in the submucosa (IC-SM) formed a loose network at the circular muscle border. These data show that the gastric antrum of the guinea pig is populated with similar classes of IC to those already described in the human and the dog. The guinea pig may therefore provide a good model for investigating the physiological roles of IC in the stomach of larger mammals.