The ultrastructure of the gastric mucosa in normal and hypophysectomized rats Supported in part by research grants from the USPHS (AM-00131–13) and The Upjohn Company. From a thesis submitted in partial fulfillment of the requirements for the Doctor of Philosophy degree in Anatomy, University of Michigan.

Abstract

The objectives of this study were to observe with the electron micro scope (a) the epithelial cell types found in the neck and isthmus of the gastric fundic gland of the rat, and (b) the effects of hypophysectomy on the gland. The following cell types were distinguished in the neck of the fundic gland of the rat: nondifferentiated cell, immature surface cell, mucous neck cell, and neck parietal cell. In the normal gland, these cell types resembled each other in the possession of a ground cytoplasm and nucleoplasm of low density, a poorly developed endoplasmic reticulum, few mitochondria and numerous free ribosomes. The most important structural difference between mucous neck and immature surface cells was the contrasting density of the secretory granules; both cell types differed from the nondifferentiated cell primarily in the presence of their characteristic secretory granules. The neck parietal cell appeared to be a developmental form between the immature surface cell and the mature parietal cell. No changes were observed in these cells to result from hypophysectomy. Hypophysectomy caused marked involutional changes in the chief cell which involved mainly the organelles most directly concerned with protein synthesis, i.e., the ergastoplasm and Golgi apparatus. These effects were correlated with the loss of basophilia and secretory granules and with the reduction in cell size and capacity to secrete pepsinogen which were described previously. In contrast, the parietal cell, which is concerned with electrolyte transport, was affected much less.