Stereological studies on the rat small intestinal epithelium. III. Effects of short-term alloxan diabetes.

Short-term experimental diabetes was used to explore the effect of hyperplastic adaption of the small intestine mucosa on the structure of its absorptive cells. Diabetes was induced in adult female rats by intravenous alloxan administration under kidney protection; similar rats, injected with physiological saline, served as controls. Quantitative light microscopy, performed after 1 month of diabetes, revealed structural changes in the jejunal mucosa consistent with hyperplasia. These changes comprised increased height of the villi (31%) and increased depth of the crypts (34%) in comparison with the control rats. At the electron microscopical level, stereological measurements of the jejunal absorptive cells revealed a decrease in their apical surface area, both for the apical surface density (24%) and for the enlargement factor due to the microvilli (12%). In the duodenal mucosa, this kind of experimental diabetes did not induce any significant light microscopical or electron microscopical changes of the villi, the crypts, or the absorptive cells. It was concluded that the adaptive capacity of the structure of the small intestine mucosa to short term experimental diabetes is more pronounced in the jejunum than in the duodenum, and that the adaptive response also includes alterations in the structure of the absorptive cells.