The tubulovesicular system of gastric parietal cells is connected to the intracellular canaliculus, rough endoplasmic reticulum and Golgi complex. A study by high resolution scanning electron microscopy.

The three-dimensional configuration of the tubulovesicular system of resting rat gastric parietal cells was determined by ultra-hihg-resolution scanning electron microscopy (SEM). Rat gastric mucosae were fixed in 1.0% glutaraldehyde and 0.5% formaldehyde in cacodylate buffer, (334 milliosmoles/kgH2O (mOsm)). To render cytoplasmic membranes visible by SEM, fixed mucosae were frozen and fractured, and the cytoplasm of fractured parietal cells was macerated by the aldehyde-osmium-DMSO-osmium procedure. With much of the cell matrix and filaments removed, SEM revealed numerous 30-60 nm tubukes, which formed a meshwork and also small cisternae about 100 nm. Some cisternae had a small, central 10 nm fenestration. The cytoplasmic surface of the tubules was smooth surfaced but some cisternal areas had attached polyribosomes. Isolated vesicles or tubules were not found in adequately macerated parietal cells. The tubulocisternal network was also connected to the Golgi apparatus. In favorable sites connections of the tubular membranes to the canaliculi were clearly visible. Continuity between these two membrane compartments suggests the probability of rapid membrane transposition when cells are stimulated to secrete acid.