The Fine Structure of the Tubulovesicular System in Mouse Gastiic Parietal Cell Processed by Cryofixation Method

Abstract

The parietal cell of rapidly frozen, substitution fixed mouse gastric mucosa was studied by thin section electron microscopy. The ultrastructural features of the cell were generally similar to those of conventionally fixed materials, but some differences were observed. Special attention was directed to determine the relationship betweenthe plasmalemma and the cytoplasmic tubular membranes. The latter was composed of a well-developed tubular system. individual tubular components 50 to 70 nm in diameter were curved, branched, or tortuousin shape and5had few varicosities or swellings. They were frequently arranged perpendicular to the plasmalemma of the intracellular secretory canaliculus and were very close to, but never continuous with the surfacemembrane. The space between two membranes was as close as 10 nm. Some parietal cells contained numerous coated vesicles, attached to the ends of the tubules, on the cell membrane, or free in the cytoplasm. Mitochondria has a dense matrix and angulated cristae, and were often joined as a beaded chain with narrow constrictions.