title: Ultrastructural and cytochemical studies on the cytodifferentiation of duodenal endocrine cells.
abstract: The development of cytodifferentiation of endocrine cells that produce the gastrointestinal hormones gastrin, cholecystokinin and secretin have been studied by a combined fluorescence-cytochemical, immunocytochemical and ultrastructural approach. The results show that, during development, several ultrastructurally distinct cell types exhibit COOH-terminal gastrin and cholecystokinin immunoreactivity. Furthermore, some cells simultaneously contain both gastrin- and cholecystokinin-specific antigenic determinants. Studies on the time course of development of gastrin and cholecystokinin cells, together with the above-mentioned data, suggest that gastrin cells may be converted into cholecystokinin cells in development. During this period, gastrin, cholecystokinin and secretin cells store the biogenic monoamine, 5-hydroxytryptamine a feature not displayed by the adult counter-parts of these cells. In the adult duodenum, characteristic enterochromaffin (EC) cells store 5-hydroxytryptamin for which, evidence for a possible hormonal role has been presented. Taken together, our data indicate that the differentiation of duodenal endocrine cells occurs in distinct steps, each involving a restriction in the biosynthetic repertoire of the cell.
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002766:Cholecystokinin / Q000096:biosynthesis; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D004386:Duodenum / Q000196:embryology* / Q000378:metabolism / Q000648:ultrastructure; D004759:Enterochromaffin Cells / Q000648:ultrastructure; D005755:Gastrins / Q000096:biosynthesis; D006651:Histocytochemistry; D006801:Humans; D007124:Immunoenzyme Techniques; D051381:Rats; D012633:Secretin / Q000096:biosynthesis
chemical_list: D005755:Gastrins; D012633:Secretin; D002766:Cholecystokinin