[The ultrastructure of the epithelial endocrinocytes of the appendiceal mucosa in the human fetus].

An electron microscope study of the epithelium of vermiform processes of 11-26 week old human fetuses showed seven types of endocrinocytes differing in ultrastructure and dimensions of secretory granules. In addition to the six known types of endocrinocytes (EC, D, D1, I, L and P), endocrinocytes of a 7th type were discovered which are beyond the International classification of endocrinocytes of the gastroenteropancreatic system. The overwhelming majority of endocrinocytes of the vermiform process epithelium form EC-cells. Besides, cells of a "mixed" type, both exo-endocrine and endo-endocrine cells, were revealed.