Electron microscopic observations of surface mucous cells in the mouse gastric mucosa during physiological...

The gastric mucosa of adult mice was observed by electron microscopy, and the following findings were obtained. Surface mucous cells mostly undergo degeneration in situ before extrusion from the mucosal surface. Degenerating cells exhibit low electron density of the cytoplasmic matrix and interchromatin region of the nucleus. Some vacuoles can be seen in the cytoplasm. The rough endoplasmic reticulum and Golgi complex retain their normal configurations. Mitochondria are condensed. Lysosomes increase in number, and acid phosphatase activity is restricted within them. Massive exocytotic release of mucus is seen at the cell apex. The basolateral plasmalemma seems intact until the latest stage of extrusion. At the tight and gap junctions, the outer leaflets of apposing plasmalemmas remain fused. On the other hand, microfilaments and tonofilaments are dissociated from the intermediate junctions and desmosomes, respectively, during degeneration. Massive discharge of mucus and well preserved basolateral plasmalemma of the degenerating cell may restrict the back-diffusion of gastric juice into the mucosa to a minimum level during the degeneration and extrusion processes.