Selective double staining of interstitial cells of Cajal and macrophage-like cells in small intestine by an improved supravital methylene blue technique combined with FITC-dextran uptake.

By a brief exposure of small intestine (mouse, rat, guinea pig) to lysolecithin prior to vital methylene blue staining we were able to demonstrate in a selective way the complete network of interstitial cells of Cajal, located in the space between the longitudinal and circular muscle layers. A combination with fluorescence labeling (FITC-dextran uptake) of macrophage-like cells, allowed us to demonstrate 1) the complete, regular distribution of both cell populations along the entire small intestine, and 2) the constant, intimate associations between interstitial cells of Cajal and macrophage-like cells. In relation to current hypotheses concerning a role of interstitial cells of Cajal in motility regulation, our results call attention to the possible involvement of another cell type, the macrophage-like cell.