Identification of cholecystokinin-secreting cells.

Cholecystokinin (C.C.K.)-producing cells were identified in the mucosa of the upper small intestine in man and other mammals by immunocytochemical techniques and electron microscopy on semi-thin and serial thin sections. Ultrastructural studies suggested that the C.C.K.-producing cells resemble I cells of the modified Wiesbaden classification. The combination of these techniques provides a simple and reliable method of identifying C.C.K. cells in human biopsy material and will be useful in the investigation and diagnosis of gut endocrine dysfunctions.