The aged rat pineal gland as revealed in SEM and TEM

This study utilized SEM and TEM to demonstrate and compare age-associated changes in pineal morphology of young and senile rats. Structural changes observed in this study and interpreted as age-related included (1) an Increase in the overall thickness of the connective tissue capsule with age, (2) an increase in the relative number of connective tissue cells and fibers in the aged pineals, (3) an increase in the number of striated muscle fibers in the connective tissue capsule and pineal parenchyma, (4) increased number of vacuoles, dense vesicles and dense bodies in pinealocytes, (5) mitochondria with dense cores and longitudinally arranged cristae, (6) an increase in size of cytoplasmic lipid droplets and presence of interstitial adipose lobules, (7) the presence of myelin-like figures in the stalk of the pineal gland and (8) an increase in the number and size of concretions in the aged rat pineal. In addition, the post-ganglionic sympathetic nerve fibers and vascular elements were also compared in the two age groups.