FRAR course on laboratory approaches to aging. The role of pathology in rodent experimental gerontology.

The distinction between aging and age-related disease is a blurred one at best. Pathologic lesions and diseases, while having obvious importance for the well-being of an individual, are not more indicative of aging than are silent or benign aging changes. All lesions are useful as biomarkers of aging. They are definable, and can be characterized in terms of their prevalence and severity in different species, genotypes, genders, and age groups. Some data from previous studies are presented as examples. Many lesions of aging are quite restricted, in terms of prevalence or severity, to specific genotypes, species or genders. Recognition of the very great diversity of lesion biomarkers between genotypes, genders and species should prevent investigators from extrapolating findings in one genotype-gender to any other.