| Popis: |
By electron microscopy, the mucosal epithelium of a distal part of the intestine of humans and other vertebrates (Rana temporaria, Lacerta vivipara, Columba livia, rabbit, rat, pig, cow) was examined. On the basis of the variety of cellular structure and the level of specialization of the involved elements a common regularity of ways of differentiation of endocrine cells was revealed. The updating of endocrine cells basically occurs as a result of differentiation of cambial cells through intermediate pre-enteroendocrine forms. Reorganization of exocrine epithelial cells is accomplished through "mixed" exo-endocrine cells. At the lower vertebrate animals the "mixed" cells are met much more frequently than in mammals, including man. In humans the greatest quantity of these cells is observed in the intra-uterine period of development and in cases of pathology. Ways of cytogenesis in endocrine cells are differently manfested in the course of ontogenesis and under broken ability to live. |
