Histological and ultrastructural changes of the thyroid follicles after injection of vitamin C in aged male albino rats

This study was conducted to investigate the effect of vitamin C administration on the structure of thyroid follicles in aged albino rats. Forty eight male albino rats were used in this study. They were divided into two groups [24 adult and 24 aged]. Each group was divided into 3 subgroups [8 animals served as controls, 8 animals received intramuscular [i.m.] injection of 50 mg/kg/day vitamin C and 8 animals received i. m. injection of 100 mg/kg/day vitamin C]. After three weeks all animals were sacrificed. The thyroid gland was dissected out and prepared for light and electron microscopic examination. Morphometric studies were done to compare the diameter of the follicles and the height of the follicular cells in the different groups. Histological examination and morphometric studies revealed that extremely large follicles appeared in the aged rats. These follicles were lined by attenuated follicular cells. Electron microscopic examination revealed that the cytoplasm of the follicular cells was occupied by dilated rough endoplasmic reticulum, secondary 1ysosomes and large number of cytoplasmic vacuoles that contained colloidal material. On the other hand, sections of aged animals that were injected with vitamin C showed some improvement in the follicular structures. Moreover, the follicular cells became nearly similar to the adult control group. These results provided evidence that supplementation of antioxidant vitamin C could play an important role in the modulation of the thyroid changes that were associated with aging