ELECTRON MICROSCOPY OF THE OXYNTIC CELL IN THE GASTRIC GLANDS OF THE BULLFROG (RANA CATESBIANA)

Abstract

A B S T R A C TThe fine structure of the oxyntic cell from the gastric glands of the bullfrog was studied in lead hydroxide-stained sections of gastric mucosa fixed in buffered osmium tetroxide and embedded in n-butyl methacrylate. The oxyntic cell in non-acid-secreting stomachs (gastric juice pH, 7.4-7.8) is characterized by: (a) numerous closely packed smooth surfaced vesicular and tubular profiles disposed randomly in the cell; some of these elements show interconnections making it possible to identify this component with smooth surfaced endoplasmic reticula of certain other cell types, (b) a small percentage of rough surfaced profiles characteristic of endoplasmic reticula possessing RNP particles on the outer membrane surfaces, (c) a Golgi complex consisting of multiple isolated non-polarized arrays of smooth surfaced parallel elongated profiles and associated vesicular elements, (d) a sparse granular component (140 A) scattered freely in the cytoplasmic matrix, (e) numerous mitochondria with a dense matrix and containing an unusually large number of closely approximated cristae, (f) a number of zymogen granules consisting of either a dense body limited by a membrane or surrounded by a halo of less dense material which is in turn limited by a membrane, and (g) a number of granules (~260 A) containing several smaller granules (~8 0 A) identified presumably as glycogen. Intracellular canaliculi were not observed. Instead the free surface of the oxyntic cell facing the lumen of the gastric gland shows a complicated plication of the plasma membrane. Intercellular canaliculi are seen frequently between adjacent oxyntic cells. The walls of these canaliculi are made up of folded and ruffled cell membranes. The basal surface of the cell also exhibited this type of configuration. Occasional smooth surfaced profiles are seen communicating with the free surface, the wall of an intercellular canaliculus, or the basal surface of the cell. Although nerve endings were not found in association with oxyntic cells, unmyelinated nerves were observed in the vicinity of the gastric glands.

Computer modeling of gastric parietal cell: significance of canalicular space, gland lumen, and variable canalicular [K+]

“…Examination of many of our micrographs of adult rabbit gastric mucosae revealed ϳ200 gastric glands per linear cm, thus ϳ40,000 glands/cm 2 . Diameter of a single gland lumen, modeled as a simple cylindrical tube, was approximated as 3 m (35,48,49), resulting in a total ϳ0.003 cm 2 of cross-sectional luminal area through which parietal cell secretion would flow to exit 1 cm 2 of flattened mucosa. A gland luminal length of 300 m was chosen for distance from mucosal bath to an average parietal cell (16).…”

ELECTRON MICROSCOPY OF THE OXYNTIC CELL IN THE GASTRIC GLANDS OF THE BULLFROG, RANA CATESBIANA

“…After KMnO4 fixation, the oxyntic cell in the gastric glands of the frog is seen to contain many of the components previously described after OsO4 fixation in the same and other species (9,7,8,2),…”

“…It seems reasonable to identify the bulk of this system as the agranular endoplasmic reticulum since the granular reticulum constitutes only a small percentage in the oxyntic cell of the frog (7). It is apparent, after comparing the endoplasmic reticulum observed here following permanganate fixation with that previously demonstrated with osmium tetroxide (7), that a greater percentage of elongated profiles and relatively few vesicles are evident after permanganate fixation. Recently, using osmium tetroxide fixation, Ito (2) reported similar findings in amphibian oxyntic cells with modified preparatory procedures.…”

“…In recent studies (7,8), the fine structure of the oxyntic cell was found to change during acid secretion, The main element affected was the system of smooth surfaced tubules, cisternae, and vesicles (which represents most of the endoplasmic reticulum of this cell). In many instances, the smooth surfaced elements were found to form a reticulum or a continuous three-dimensional network.…”

Fine Structure of the Oxyntic Cell in the Chicken Proventriculus

“…Ilelamler 119621). Oxyntic cells of the bullfrog (Sedar [1961]) and the chicken lack these canals. Am phibian gastric glands have intercellular canaliculi w ith distinct lum ina (Sedar 11961]).…”