Histological and Morphometric Studies on the Age-Associated Changes in the Colon of the Mouse

Abstract

The present work was designed to study the morphological and morphometric age-associated changes in the mouse colon in order to explore any changes that might lead to colon dysfunction.

Forty mice were used in this study. They were divided equally into four groups aged 1, 2, 12 and 24 months. Light microscopy and scanning and transmission electron microscopic examinations of the colon were conducted. Measurements of the outer diameter of the colon, the total wall thickness, the crypt's length and the muscle coat thickness were carried out. Statistical analyses of the results were done. In old aged mice (12 and 24 months) there was apparent decrease in the number of goblet cells and marked increase in the amount of collagenous fibers in the mucosa and submucosa compared to the young aged mice (1 and 2 months). Statistical analysis showed a significant increase in the outer diameter and the length of the crypts in old aged mice. In addition a significant decrease in the nerve cell number of Auerbach's plexus was also recorded. Using TEM there was an apparent reduction in both the striated border and the intercellular spaces in the mucosal epithelium of the old mice. In addition there was a marked increase in the undifferentiated stem cells at the bases of the crypts. Using SEM many areas of denuded epithelium were also observed in old mice. The remarkable decrease in (1) the number of mucosal goblet cells and microvillar and intricate systems, (2) the number of neurons and interstitial cells of Cajal in the myenteric plexus, (3) the muscle wall thickness, with the observed increase in deposition of collagen fibers in the mucosa and submucosa of old-aged mice colon probably contribute to colon dysfunction in elderly.

Key words: Colonic mucosa, goblet cells, colonic crypts, collagen, Auerbach's plexus.