Morphological changes in the submandibular gland of aging rats.

Age-related histological changes in submandibular glands of 5-, and 24-month-old Sprague-Dawley male rats were compared qualitatively using semi-thin sections of epoxy-embedded glands. Atrophy of acini and granular ducts with a concomitant hyperplasia of intercalated ducts were the dominant features seen in the 15- and 24-month-old glands compared to 5 months. In both aged groups (15 and 24 months) there appeared structures similar to terminal tubules normally seen during development. At 15 months irregular ducts consisting of a mixture of agranular cells and granular cells typical of granular ducts were found in continuity with the hyperplastic intercalated ducts. The significance of these age-related morphological changes remains speculative.