Age-related morphological changes of rat submandibular gland

―The acinic cells―

Abstract

Age-related changes of rat submandibular gland were studied by light and electron microscope with special reference to the acinic cells. Male SD rats were studied. 2, 4, 6, or 12-month-old rats were used for the young and adult group and 22-month-old rats were used for the aged group. The acinic cells of the rat submndibular gland of the young and adult group were well developed, were rich in rough endoplasmic reticulum and Golgi complex, and had secretory granules composed of well defined amorphous material

Light microscopy of the acinic cells of the aged group showed some regressive changes, such as pyknotic and bizarre nuclei, irregularity in size, atrophy, vacuolar degeneration and a decrease in the stainability of PAS and toluidine blue stain, when compared to those of young and adult group.Ultrastrucuturally they were characterized by a decrease in the amount of rough endoplasmic reticulum, an increase in size and in the amount of lipofuscin granules, and many secetory granules being composed of loose amolphous material. Secretory granules of the aged cells sometimes fused to make a big secretory granule which might result in a vacuole under light microscopy.