[Differentiation and cytogenesis of endocrine elements of the rat duodenum in ontogenesis]

Duodenal endocrine apparatus was studied in rat during individual development using electron microscopy. Endocrinocyte differentiation was demonstrated to occur in embryonic period and it is characterised by fast cytotype number growth. During embryogenesis processes of endocrinocyte differentiation occur more intensely than in adult animals which is manifested by higher incidence of different types of incretory elements in embryos. By the moment of birth EC-, L-, S-, D-, D1-, P and I-cells can be identified in the duodenal epithelium at different stages of differentiation as well as "mixed" exo-endocrine cells. The presence of transitory cellular forms from agranular elements up to mature differentiated endocrinocytes and "mixed" exo-endocrine cells reflects cytogenetic processes in population of endocrine cells and allows to consider duodenal epithelium both structurally and functionally as a tissue with common histogenetic basis.