Cytology of ?-cells in rabbit pancreas pieces incubatedin vitro; Effects of glucose and tolbutamide

Autor: J. A. Findlay, J. D. Lever, G. Irvine, J. R. Gill, P. J. Randle
Rok vydání: 1968
Předmět:
Zdroj: Diabetologia. 4:150-160
ISSN: 1432-0428
0012-186X
DOI: 10.1007/bf01219436
Popis: The electron microscopic appearances of rabbit pancreas β-cells takenin vivo and afterin vitro incubation have been compared and the effects of high glucose and tolbutamide stimulation of insulin releasein vitro on β-cell cytomorphology investigated. Normal structure was maintained onin vitro incubation in a proportion of β-cells; this varied in different samples from 35–100 per cent. The cause of this variation was not apparent but it was not influenced by the time of incubation, medium glucose concentration or tolbutamide. Quantitative measurements have been made of the proportion of β-cell profiles showing marginal distribution of granules, of the number of contacts between granule sac membranes and the plasma membrane, of the number of granule sacs showing perforations, of the population density of specific secretion granules, lysosomes and autophagic bodies, and estimates have been made of the extent of the Golgi apparatus in cross section. No consistent change in these parameters was observed following stimulation of insulin release with glucose or tolbutamide. There was no evidence in any of the specimens examined of continuity between the interior of a granule sac and the outside of a β-cell. Calculations based on the rate of release of insulin and the insulin content of the pancreas indicate that the chance of visualising granule extrusion by electron microscopy is small. The significance of these results in relation to the emiocytosis theory of insulin release (Lacy andHartroft) is discussed.
Databáze: OpenAIRE
Externí odkaz: