Effect of Aging on the Histological Structure of the Colon of Male Albino Rat Light and Electron Microscopic Study

Introduction: Aging is the impelling cause behind age related diseases. The colon, as a part of the gastrointestinal tract, is impacted by aging. Elders frequently complain of constipation, fecal incontinency and fecal impaction, that affects their life and causes morbidity.Aim: To examine aging impact on the histological structure of the colon wall in male albino rats. Materials and methods: A total of thirty male albino rats were equally split into three groups: young, adult and senile, rats aged six weeks, 16 weeks and two years respectively. Colon specimens, one cm over the ileocecal valve, of all rats were collected, processed then examined by light and transmission electron microscopes. Hematoxylin and eosin, toluidine blue, alcian blue-PAS technique and Masson’s trichrome were used to stain the sections then morphometrical measures and statistical analysis were carried. Results: The layers of the colon were affected by aging on the microscopical level. Localized mucosal and epithelial interruption, mononuclear cellular invasion and goblet cells’ mucous load change were revealed in senile rats. Collagen expansion in all layers was also depicted. Significant decline of myenteric plexus neurons’ Nissls’ granules and goblet cells’ number were recognized. Colonocytes of aged rats displayed deformed nuclei, localized microvilli loss, vacuoles within cytoplasm and mitochondrial swelling with deformed cristae. Conclusions: It was concluded that aging caused profound structural and ultrastructural changes in senile rats’ colon. The changes in turn are thought to alter colonic function, which might contribute to aging associated diseases. Key words: colon, rat, transmission electron microscope, aging.