The comparative ultrastructure of the pancreatic islet of Langerhans

Sato, Tomohiro; Herman, Lawrence; Fitzgerald, Patrick

doi:10.1016/0016-6480(66)90094-3

Cited by 74 publications

(30 citation statements)

References 21 publications

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“…Periodicity in beta granules observed in thin sections has previously been reported in beta granules of the congo eel, tiger salamander, and the dog (Sato, Herman, and Fitzgerald, 1966) . McGavran, as reported by Lacy (1967), observed periodicity in the beta granule of a human islet .…”

Section: Discussionsupporting

confidence: 63%

Isolation and Properties of Secretory Granules From Rat Islets of Langerhans

Greider

Howell

Lacy

1969

The Journal of Cell Biology

125

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Beta granules isolated from rat islets of Langerhans and subjected only to phosphotungstic acid had, in negatively stained images, a 50-A periodicity . This periodicity was also observed in thin-section profiles of beta granules in intact cells . In shadowed preparations, the granules were spherical in shape and had irregular edges and surface structure . The presence of such a periodicity in the beta granule indicates that its matrix may be composed of a crystalline material .The isolation of a fraction of secretory granules from isolated islets of the rat pancreas (Howell, Fink, and Lacy, 1969) has made possible further characterization of the morphological properties of the isolated granules by methods not applicable to granules retained within the intact cell . MATERIALS AND METHODSIn most experiments, the washed pellet of the secretory granule fraction, prepared by density gradient centrifugation , was resuspended in 0.2 ml of a cold medium containing 160 mM KCI, 5 mm NaCl, 0 .5 MM MgC1 2 , and 5 mm sodium phosphate, pH 6 .0, and maintained at ice-bath temperature while samples were withdrawn . Grids were prepared as soon as the pellet had been resuspended, since the insulin content of the granules becomes progressively solubilized with time after suspension (Howell, Young, and Lacy, 1969) . All grids were prepared within 10 min of resuspension . In a single experiment, the pellet was resuspended in 2 .5% glutaraldehyde in 0 .15 M phosphate buffer, pH 7 .5 . In a further experiment, the pellet was resuspended in 0 .3 M sucrose, buffered at pH 6 .0 with 0 .005 M phosphate buffer .For negatively stained preparations, a small drop of suspension was placed on a collodion-carboncoated 400-mesh copper grid, allowed to sit for 1 min, then drained by contact with filter paper . A drop of 2% % phosphotungstic acid, pH 6 .0, was placed on the grid and, after a minute, was drained in the same way . The first grid thus prepared was immediately placed in the vacuum chamber of the electron microscope ; other grids were prepared and allowed to dry in a Petri dish containing a desiccant .For shadow-casted preparations, after a drop of the suspension had been drained from the grid, the grid was flushed several times with distilled water for removal of salts . Some of the grids, while still wet, were subjected to osmium vapors for several minutes ; others were allowed to dry in a Petri dish containing a desiccant . The grids were shadowed with platinum at an angle of 10°, or alternatively shadowed with platinum during continuous rotation of the grid (rotational shadowing) .Secretory granule pellets, isolated islets, and pancreatic tissue were fixed in 2 .5%/%, glutaraldehyde followed by osmium tetroxide solution, dehydrated in ethyl alcohol, and embedded in an epoxy resin according to Lockwood's procedure (Lockwood, 1964) . The thin sections were stained with uranyl on

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Section: Discussionsupporting

confidence: 63%

Isolation and Properties of Secretory Granules From Rat Islets of Langerhans

Greider

Howell

Lacy

1969

The Journal of Cell Biology

125

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“…The latest studies on the ultrastructure of the pancreatic islets [56,57,58,59,60] leave little doubt that cells other than insulin-and glucagon producing cells are present in these islets. In a previous publication [I0], our group has identified two other types of islet cells, which were designated provisionnally as types III and IV.…”

Section: Discussionmentioning

confidence: 99%

Are gastrin-cells present in mammalian pancreatic islets?

1974

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Summary. The possible existence of gastrin-cells in the pancreas was investigated by a comparative immunehistological and immunoehemical study of antral mucosa and pancreas of man, dog, rabbit, rat and pig. Gastrincells were identified in the antral mucosa of all these species with the indirect immunofluorescence and the immunoperoxidase methods. With the same methods, no gastrin-cells were detected in the pancreas in any of the species studied. With radioimmunoassay, serial dilutions of antral or duodenal extracts yielded curves which were identical to those obtained with synthetic human gastrin, whereas pancreatic or islet extracts did not produce any significant displacement of the 125-Igastrin. Therefore, the presence of gastrin-producing ceils in normal pancreas remains questionable.

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“…In the rat, unlike in canine or human beta cells [9,23], secretory granules are spherical and usually homogeneous [23]. The tumor we examined seemed to retain these features.…”

Section: Discussionmentioning

confidence: 88%