Identification of gastrin-secreting cells and cholecystokinin-secreting cells in the gastrointestinal tract of the human fetus and adult man.

Gastrin- and cholecystokinin (C.C.K.)-containing cells were detected by using anti-gastrin and anti-C.C.K. sera in the gastrointestinal tract of human fetuses and premature infants and in the stomach and duodenum of adult man obtained by biopsy from eight patients with normal gastro-duodenal endoscopy. The specificity of immunocytological reactions was ascertained by studying the inhibition of the reaction by gastrin, C.C.K., secretin, somatostatin, glucagon, insulin, serotonin, histamin, caerulein and octapeptide of C.C.K. In adult man, the gastrin cells are located only in the antrum and juxtapyloric region; C.C.K. was detected in the duodenum. In the human fetus, the first gastrin cells are seen in the antrum at 14 weeks of age and in the duodenum as early as 10 weeks; the C.C.K. cells are seen in the small intestine at 10 weeks of age.