The structural and metabolic indicators of the function of the end secretory divisions, intercalary ducts, and salivary tubes of the salivary gland were assayed in white rats aged 20 1/2 months. This age period is characterized by the occurrence of noticeable changes in the reproductive tract and of spontaneous tumors in different organs. Abnormalities of transport processes followed by an insignificant variation in intracellular metabolism indicate that reconstitution of the salivary glands accompanied by profound shifts in endocrine regulation is a secondary process, a consequence of a systemic injury to the microcirculatory bed. Disorders seen in the processes of secretion elimination and reduced activity of lysosomal enzymes are likely to be the triggering mechanism of the occurrence of the delayed phase of storing secretory granules observed during the development of metabolic sialoses.