Histological and immunohistochemical study of changes in the albino rat pancreas during aging

ABSTRACT

The prevalence of pancreatic insufficiency increases with age. In addition, pancreatic cancer is a disease of elderly. To investigate the histological and immunohistochemical changes in rat pancreas during aging. This study was performed on fifteen male albino rats, The animals were classified into three equal groups, group A [3 months old], group B [12 months old] and group C [24 months old]. Their pancreases were dissected and processed for light and electron microscope examination. Paraffin sections were stained with H and E, Mallory's trichrome and immunohistochemical staining of beta cells by anti-insulin antibody. Area% of collagen fibers was also measured morphometrically and statistically analysd. Examination of exocrine part of pancreas in group A revealed that, it was formed of lobules packed with acini. The acinar cells appeared with euchromatic nuclei and their cytoplasm contained numerous granules, well defined RER and mitochondria. While in group B, dilated ducts were noticed. Some acinar cells had small electron dense nuclei and their cytoplasm contained dilated cisternae of RER, few granules and secondary lysosomes. In group C, most of acini were vacuolated. The acinar cells showed marked degenerative changes in cytoplasmic organelles and their nuclei were heterochromatic. There was age related increase in collagen fibers. The area% of collagen fibers was significantly increased in group C as compared to groups A and B. As regards the endocrine part of pancreas, in group A it was formed of group of cells separated by blood capillaries. beta cells had euchromatic nuclei and their cytoplasm was filled with their characteristic granules. In group B, some islets showed decreased cells population. In addition, the cytoplasm of some beta cells contained few vacuoles. In group C the prevelance of vacuolated cells that showed pyknotic nuclei was increased. Strong positive immunoreaction of insulin hormone was seen in the cytoplasm of beta cells occupying most of the islet in groups A and B. However in group C the immunoreactivity was faint. The exocrine and endocrine parts of pancreas were subjected to natural degenerative changes which increased steadily with age. So, further studies should be needed in a trial to find protective anti-aging strategies including dietary anti oxidants and stem cell therapy