Changes in the Size and Number of Secretion Granules in the Rat Exocrine Pancreas Induced by Feeding or Stimulation in Vitro. A Morphometric Study

Cell Tissue Res. 1987 Aug;249(2):427-36. doi: 10.1007/BF00215527.

Abstract

The size, number and volume per cell of secretion granules in rat exocrine pancreas have been measured using stereological techniques. The changes which occur as a result of feeding starved animals (90 min) or stimulating lobular fragments in vitro with carbachol are documented. In fasted animals mean acinar cell volume was estimated as 1670 micron 3 and the cells contained an average of around 450 secretion granules with a corrected mean diameter of 0.70 micron. They occupied around 7% of cell volume. After feeding mean cell volume was about 1300 micron 3 and the cells contained an average of about 190 granules per cell with a mean diameter of 0.58 micron. They occupied 3% of cell volume. A shift in the size frequency distribution of granule diameters occurred as a result of feeding. In vitro experiments in which lobules were induced to secrete with carbachol (10 microM, 3 h, 37 degrees C) had a similar effect. Mean cell volume was reduced from around 1760 micron 3 to 1360 micron 3, mean granule number from around 420 per cell to 180 per cell and the volume density of granules was reduced from about 8% to 3% of cell volume. There was no significant change in mean granule diameter or shift in the size-frequency distribution of granule diameters. Incubation of tissues with cycloheximide (1 mM, 3 h, 37 degrees C) did not prevent secretion by carbachol but it prevented replacement of granules. As a consequence, depletion by carbachol was greater in the presence of cycloheximide, the granules being reduced to around 110 per cell and to only 2.5% of cell volume. We conclude that feeding causes a preferential loss of larger granules and that during secretion replacement of granules occurs. Some of these granules are smaller than those evident in the glands of starved animals.

MeSH terms

  • Animals
  • Carbachol / pharmacology*
  • Cell Nucleus / ultrastructure
  • Cycloheximide / pharmacology*
  • Cytoplasmic Granules / drug effects
  • Cytoplasmic Granules / ultrastructure*
  • Eating
  • Fasting
  • Male
  • Microscopy, Electron
  • Pancreas / drug effects
  • Pancreas / physiology
  • Pancreas / ultrastructure*
  • Rats

Substances

  • Carbachol
  • Cycloheximide