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Ultrastructural changes related to functional activity in gastric oxyntic cells
The American Journal of Physiology
|November 1, 1981
Summary
Gastric oxyntic cells expand their surface area during HCl secretion. Evidence supports a membrane fusion process, where cytoplasmic membranes merge with the apical surface, rather than a pre-existing connection.
Area of Science:
- Cell Biology
- Gastroenterology
- Membrane Biology
Background:
- Gastric oxyntic cells secrete hydrochloric acid (HCl).
- Stimulation leads to significant morphological changes in these cells.
- The mechanism behind apical surface expansion during secretion is debated.
Purpose of the Study:
- To investigate the morphological changes in gastric oxyntic cells during HCl secretion.
- To differentiate between two proposed hypotheses for apical surface expansion.
- To provide evidence supporting or refuting the membrane fusion hypothesis.
Main Methods:
- Review of morphological evidence from transmission electron microscopy (TEM).
- Analysis of freeze-fracture replica studies.
- Assessment of macromolecular tracer penetration and membrane surface-staining characteristics.
- Comparative studies of membrane fractions from resting and secreting stomachs.
Main Results:
- The stimulated oxyntic cell exhibits a greatly expanded apical surface compared to non-secreting cells.
- Morphological evidence, including TEM and tracer studies, was analyzed.
- Comparative studies revealed distinct properties of membrane fractions from resting versus secreting cells.
Conclusions:
- The weight of evidence favors a membrane fusion process for apical surface expansion.
- Cytoplasmic tubulovesicular membranes fuse with the apical membrane during HCl secretion.
- This fusion is a fundamental event in the membrane transformation of the oxyntic cell.