Abstract
The fine structure of the parietal (oxyntic) cell in the gastric glands (corpus of the stomach) of the dog was examined under conditions of active gastric acid secretion and compared with cellular structure in the non-acid-secretory (basal) state. Animals, in both acute and chronic experiments, were equipped with gastric fistulae so that gastric juice could be collected for analysis of total acidity, free acidity, volume, and pH prior to biopsy of the gastric mucosa. The specimens of mucosa were fixed in buffered OsO(4) and embedded in n-butyl methacrylate and the thin sections were stained with lead hydroxide before examination in the electron microscope. A majority of parietal cells showed an alteration of fine structure during stimulation of gastric acid secretion by a number of different techniques (electrical vagal stimulation, histamine administration, or insulin injection). The changes in fine structure affected mainly the smooth surfaced vesicular elements and the intracellular canaliculi in the cytoplasm of the cell. The mitochondria also appeared to be involved to some extent. During acid secretion a greater concentration of smooth surface profiles is found adjacent to the walls of the intracellular canaliculi; other parietal cells exhibited a marked decrease in number of smooth surfaced elements. Intracellular canaliculi, always present in non-acid-secreting oxyntic cells, develop more extensively in cells of acid-secreting gastric glands. The surface area of these canaliculi is greatly increased by the elaboration of a large number of closely approximated and elongated microvilli. Still other parietal cells apparently in a different stage of the secretory cycle exhibit non-patent canaliculi lacking prominence; such cells have very few smooth surfaced vesicular elements. These morphological findings correlated with the acid-secretory state of the stomach provide evidence that the parietal cell participates in the process of acid secretion.
Highlights
Since the discovery by William Prout in 1824 [28] that the acidity in the stomach was due to hydrochloric acid, there has been a sustained interest in the mechanisms involved in the formation and secretion of gastric acid [5, 16, 18, 29, 9]
A study of the fine structure of the parietal cell under conditions of active acid production compared with the cellular structure in the non-acidsecretory state should contribute to a better understanding of the mechanism of acid formation
Examination of electron micrographs of the gastric glands from the biopsy specimen shows that ~70 to 80 per cent of the parietal cells demonstrate a definite alteration of fine structure
Summary
Since the discovery by William Prout in 1824 [28] that the acidity in the stomach was due to hydrochloric acid, there has been a sustained interest in the mechanisms involved in the formation and secretion of gastric acid [5, 16, 18, 29, 9]. It is generally accepted that the different cell types of the gastric glands proper (corpus of the stomach) in mammalian species each have a specific function and elaborate a particular cellular product [8]. A study of the fine structure of the parietal cell under conditions of active acid production compared with the cellular structure in the non-acidsecretory (resting or basal) state should contribute to a better understanding of the mechanism of acid formation. The continuous and spontaneous acidsecretory activity of the rat glandular stomach (I 1) makes studies such as those presented previously
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