The gastric gland opens at the bottom of the pit. Its mouth (isthmus) is composed of undifferentiated columnar cells that divide by mitosis and undergo renewal. While some of these isthmus cells give rise to the surface mucous cells of the crypt, others transform into the epithelial cells of the glands, that is, parietal cells secreting HCl and mucous neck cells. As these neck cells migrate toward the bottom or base of the gland, they differentiate into zymogenic cells which secrete pepsin. Parietal and zymogenic cells migrate toward the bottom of the gland where they degenerate.

At the base of the glands there are also some endocrine cells showing small granules. These cells, which secrete gastrin, like the other epithelial cells of the gland, degenerate and undergo renewal.

(\Drawing based on the work of Dr. C. P. Leblond and collaborators.