Histogenesis of the mouse gastric mucosa, with special reference to type and distribution of proliferative cells.

Histogenesis of the mouse gastric mucosa and the distribution of epithelial cells capable of proliferation were studied by light microscopy, autoradiography with 3H-thymidine and electron microscopy. The formation of the gland begins on day 14 of gestation, while morphological signs of epithelial cell differentiation begin on day 15. The cell types include surface mucous, primitive chief and parietal cells during the late prenatal and first 2 weeks of postnatal development. Immature surface mucous cells and undifferentiated cells in the lower part of the foveola and the isthmus, and primitive chief cells throughout the gland become 3H-thymidine labeled. In addition, surface mucous cells in the superficial epithelium are labeled in fetuses and neonates several hours after birth. By 21 days after birth, primitive chief cells are replaced by chief and mucous neck cells. At that time, immature surface mucous and undifferentiated cells in the isthmus, and mucous neck cells in the upper part of the neck are radio-labeled and form the generative cell zone. The mucosa attains its full thickness by 6 weeks of age. Immature parietal cells rarely incorporate 3H-thymidine during their development. It is suggested that some of the parietal cells may be derived from actively proliferating precursors, i.e., primitive chief cells and mucous neck cells in developing and adult animals, respectively.