FUNCTIONAL DYMAMISM OF GASTRIC MUCOSA BY MEANS OF HIGH-PRESSURE FREEZING METHOD

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To elucidate a functional transformation of gastric parietal cells, we have newly developed an isolated rat gastric mucosa model whose parietal cells exhibited a reverting process from the active to the resting state of acid secretion. Immunohistochemistry of proton pump demonstrated a progressive translocation of proton pump from the apical to the cytoplasmic region. At the ultrastructural level, the apical membranes were subsequently internalized into the cytoplasm forming unique penta-laminar membranes. They then formed a number of multilamellar autophagosomes that were intensely labeled for proton pump. The parietal cells exhibited well-developed Golgi apparatus and lysosomal compartments involving the multilamellar membranes. The present findings provide new insights into the functional transformation in gastric parietal cells reverting to their resting conformation.It is clinicopathologically important to elucidate the cell kinetics for the maintenance of normal gastric epithelium. In rat gastric mucosa isolated after stimulation, a number of cells were exfoliated into the gastric lumen of the pit region. It was undertaken to clarify the origin of exfoliated cells and their histochemical profiles by taking the advantages of cryotechniques. Most of the exfoliated cells were identified as pit-parietal cells labeled with both peanut-lectin and anti-proton pump antibody. Quantitative analysis verified a time-dependent increase in the number of exfoliated cells in the gastric mucosa isolated after stimulation. Most of the exfoliated cells were negative to the apoptotic markers such as TUNEL staining and caspase-3. Ultrastructurally, autophagusome-like structures consisting of proton pump positive membranes were frequently seen in the exfoliated pit-parietal cells. In addition, the pit-parietal cell exfoliation was accompanied by sealing of their basal portion with the cytoplasmic processes of adjacent surface mucous cells.