To develop and establish healthy aged rodents useful in studies on geriatric medicine, and to research their aging. Since aging in animals is influenced by species, strain, and gender, we are determining at which months they can be most effectively used in terms of their survival and morbidity. We indicated the importance of soundly aged animals and the difficulty of farming them, and explained the confusion in the F344 rat strain (differences in survival between F344/N and F344/Du, variations of F344/Du between the U.S and Japan) base on differences among the substrains (Note). Clarifies the mechanisms of aging in animals with a focus on the oral cavity and its surrounding area, the respiratory system, blood pressure, and the endocrine and genital systems. As age-related changes in rats, we described the development of dental caries and periodontal disease, alveolar diameters becoming irregular with age, a decrease in blood pressure, disruption of the layered structure of the adrenal cortex, and cessation of reproductive cycles and the lifelong survival of the ovarian follicle and the corpus luteum. Comparing age-related changes in rats (see above) with those in humans, we demonstrated that some of these changes are common between animals and humans and others are not, emphasizing the need to be careful in aging studies using animals. We research age-related changes in animals to obtain results contributing to geriatric medicine. Note： Even an inbred strain, intended to produce genetically homogeneous individuals, may be separated by countries, institutions, and researchers' moves, and its properties may alter with time. To avoid confusion, the strain after being separated is called substrains, which are often represented by the strain name and the institution symbol (ex. F344/N). back to index