Abstract
The present (Wiesbaden) classification of gut endocrine cells relies mainly on ultrastructure and the results of silver impregnation. Correlation with hormone production requires parallel immunology but conventional immune cytochemistry is, in most cases, difficult or at present impossible. The serial, semithin-thin-section technique offers an alternative, which provides absolute correlation between cell type and hormone production. The successful use of the technique is illustrated here by localization of motilin in the enterochromaffin cells of the small intestine.