Structural changes in aged cornea of male albino rat electron microscopic study

ABSTRACT

Aging is the accumulation of adverse changes that increase the risk of death. These changes can be attributed to development, genetic defects, the environment, disease and the inborn aging process. The aim of this work is to detect the ultra structural histological changes in the aged cornea of rat since little illustrative micrographs were observed. Twenty male albino rats with average weight 100-250 gm. were used in this study. They were divided into two groups. Group 1, included ten adult rats, 6-12 months old. Group 11 included ten aged rats, 18-24 months old. The animals were sacrificed and corneal specimens were taken, processed and examined ultrastructural alterations using transmission and scanning electron microscope. Adult cornea of group I showed its five histological layers. Corneal epithelium appeared lying on the basement membrane. Bowman's membrane was seen under epithelium with its randomly crossing collagen fibrils and interfibrilar substances. Corneal stroma comprised 90% of' corneal width showing well organized lain ellae of collagen fibrils with fibrocytes [keratocytes, squeezed in between fibrils. Decsemnet's membrane, a thick homogenous acellular layer separating stroma from endotheliun. Endothelial cells appeared regularly arranged flat cells with, well apparent organelles, vesicles and basal invaginations. Aged cornea of group II showed Focal degenerative changes throughout the layers of the cornea. Surface of the cornea showed abrasions, cracks and decrease of surface microvilli. Epithelial cells showed degenerative frature5 and increase invaginations. Basement membrane appeared thickened and distorted with unapparent hemidesmosomes. Bowman layer appeared losing its proper histological pattern of collagen fibrils. Corneal stroma showed areas of disorganized collagen fibrils, degenerated fibrocytes and occasionally seen Neutrophils. Descemet's membrane showed apparent thickening. Endothelial cells appeared irregular, shrunken with degenerated cytoplasm