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Gastric oxyntic cell structure as related to secretory activity
T. Ogata
Department of Surgery, Kochi Medical School, Nankoku, Kochi, Japan
Offprint requests to: Prof. Takuro Ogata, Department of Surgery, Kochi Medical School, Nankoku, Kochi, 783, Japan
Summary. The oxyntic, or parietal cell has two
characteristic membrane systems. The mammalian intracellular
canaliculi are specialized networks of narrow
channels lined with numerous microvilli. The other
common to all oxyntic cells is the tubulovesicles, a
system of tubules and vesicles. The tubulovesicular
compartment is drastically depleted during maximal
gastric acid secretion and this is coincident with an
increase in the cell surface membrane area. A plausible
explanation of this process is the fusion and transfer of
tubulovesicular membranes to the plasma membrane.
However, for many years there was no convincing
evidence of the connections between these two
membrane systems. How the tubulovesicular membranes
transform into plasma membrane without demonstrable
connections has been an enigma to electron microscopists.
Recent ultra-high resolution scanning electron
microscopic observations on the rat oxyntic cell treated
with aldehyde-osmium-aldehyde method revealed that in
the resting stage, the tubulovesicles were isolated
spherical vesicles. But after tetragastrin stimulation, they
were interconnected by slender connecting tubules
forming a tubulovesicular network. Then this network
was fused to the intracellular canaliculus at relatively
few points. These connections between the tubulovesicles
and luminal surface membrane was also
demonstrated in the frog oxynticopeptic cells. In this
review, these membrane transformations as well as
changes of the H+/ K+-ATPase, the lectin binding
glycocalyx and the cytoskeleton during secretion will be
illustrated and discussed. Histol Histopathol 12, 739-754
(1997)
Key words: Oxyntic cell , Parietal cell, Membrane
system, Stomach, Scanning electron microscopy
DOI: 10.14670/HH-12.739
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