Morphological Characteristics of the Hippocampus in OXYS and Wistar Rats during the Aging Process

Light and electron microscopy studies were performed to evaluate structural changes in the hippocampus in prematurely aging rats of the OXYS strain ( n = 20) and Wistar rats ( n = 20) as they aged. Light microscopy showed neurons with signs of chromatolysis in fields CA1 and CA3 and the dentate gyrus of the hippocampus, along with hyperchromic neurons, providing evidence that OXYS rats had signs of degeneration as early as age four months. By 18 months of age, structural changes developed in all areas of the hippocampus in OXYS rats. Ultramicroscopy studies at age four months identified that these animals showed signs of destruction of mitochondria and accumulation of lipofuscin granules; these changes progressed with age, such that animals aged 18 months were characterized by significant organelle destruction. The data obtained here provide evidence of more extensive age-related changes to neurons in OXYS rats than in Wistar rats.