Histogenesis of the mouse pyloric mucosa with special reference to the development of surface mucous cells and pylorocytes, and the formation of the generative zone.

ABSTRACT

The distribution of proliferative cells and maturation of epithelial cells were studied in the pyloric mucosa of developing mice by 3H-thymidine autoradiography, carbohydrate histochemistry and electron microscopy. The formation of the gastric foveola and pyloric gland were seen to begin as an invagination in the epithelial surface and/or the formation of intraepithelial cavity on day 13 of gestation (day E13). Surface mucous cells and pylorocytes were first identified on day E16 by carbohydrate staining as well as by their fine structure. Both types of cells rapidly acquired abundant membranous organelles and secretory granules within the first postnatal day, maturing in fine structure by day 28. Proliferative cells were distributed over the epithelium by day E15, while they were rarely found at the mucosal surface after day E16. Concomitantly with the elongation of foveolae and glands during postnatal development, the proliferative capability of surface mucous cells diminished from the foveolae and that of pylorocytes from the glands, respectively; the generative zone was restricted to the isthmus by day 21, as in the adult animal. These results reveal that the histogenesis of the mouse pyloric mucosa is accomplished by the end of the weaning period.