Developmental profile of chromogranin, hormonal peptides, and 5-hydroxytryptamine in gastrointestinal endocrine cells.

In this immunocytochemical study, we have analyzed the developmental profile and phenotypic expression of the endocrine cell antigens chromogranin, 5-hydroxytryptamine, gastrin/cholecystokinin, cholecystokinin (9-20), somatostatin, somatostatin 28 (1-14), somatostatin cryptic peptide, glucagon, glucagonlike peptides 1 and 2, glicentin, peptide YY, glucose-dependent insulinotropic peptide, secretin, neurotensin, and substance P in human fetal stomach and intestine. All currently identifiable endocrine cell types were detected by 10 wk of gestation. Immunostaining for the endocrine cell marker chromogranin revealed abundant endocrine cells in the earliest specimens (8 wk of gestation) with a relatively higher frequency in both proximal duodenum and distal colon/rectum compared with other areas. Quantification of endocrine cells showed an increase with age that was roughly parallel to the growth of the gut as a whole. These studies show that the diversity of the endocrine component of the gut appears to be established by 10 wk of gestation and that gut activity is preceded by the development of a fully differentiated endocrine component, which may subserve or even initiate the onset of functional maturity.