Electron Microscope Studies on the Gastric Mucosa of Normal Rats

The mucous membrane of the glandular stomach of rats fixed in one percent osmium tetroxide was observed with the electron microscope.1. The body chief cell can be identified by the presence of abundant endoplasmic reticulum and secretory granules and vacuoles, which are almost transparent to the electron beam. Presumable transitions may be observed, among the inclusions mentioned above. The typical GOLGI apparatus is located at the supranuclear region, and long filamentous mitchondria are numerous at the cell periphery.2. The parietal cell is characterized by the position of the cell, the presence of intracellular secretory capillaries and a multitude of large mitochondria; which are nothing but the so-called oxyntic granules, in which unusually close packing of cristae mitochondriales is recognized. No typical GOLGI apparatus is observed, and the rough surfaced endplasmic reticulum is scanty. Vesicles of the smooth surfaced endosplasmic reticulum, however, are richly contained throughout the cytoplasm. The intracellular capillary is provided with remarkable microvilli. From the free surface into lumen, extend a huge protoplasmic protrusion, which is of fine granular texture of almost homogeneous appearance and contains no mitochondrion. This figure may suggest a possibility of the presence of apocrine secretion in this cell.3. The mucous neck cell may be distinguished from other cells by the irregularity of nuclear outline and the density of secretory granules, which is higher than those of body chief cells but lower than those of surface epithelial cells. The well developed GOLGI apparatus is situated among the secretory granules, to which the apparatus is often applied closely. Sometimes small granules similar in density to secretory granules are observed within the GOLGI area, suggesting an intimate relationship between the GOLGI apparatus and the mucus production. Endplasmic reticulum of the rough surfaced type and long filamentous mitochondria are repelled to the peripheral parts of the cell.4. In the above cell types, i. e., the body chief, parietal and mucous neck cells, a peculiar behaviour of mitochondria was noted. Namely, mitochondria are often attached to the lateral plasma membrane at a thickened part shortly beneath the terminal bar.5. The argyrophile cell (basal clear cell) contains small specific granules and fat droplets. Mitochondria of this cell are extremly slender. The GOLGI apparatus and rough surfaced endoplasmic reticulum are less developed in this cell type.6. The surface epithelial cell shows a characteristic accumulation of dense secretory granules of somewhat irregular outline at the apical end of the cell. This cell always contains well developed GOLGI apparatus, within which spherical granules of various sizes considered as probable forms of immature secretory granules are contained. Small dense particles presumable to contain the ribonucleoprotein are abundant in this cell. Remarkable foldings of lateral intercelllular boundary, the interdigitations, are observed.