Ultrastructure of parathyroid glands in triamcinolone-treated mice

6 weeks old ICR strain mice were given 21 daily injections of the synthetic glucocorticoid, triamcinolone diacetate (8 mg/kg body weight) and their parathyroid glands were examined by light and electron microscopy and compared with untreated litter-mate controls. Parathyroid glands are composed of a single basic cell type, but some cells are electron-dense ('dark' cells) and some less dense ('light' cells). There is considerable variability in numbers of light and dark cells from gland to gland. Following triamcinolone treatment the cells are arranged more in whorls, and there is a relative increase in the numbers of 'light' cells, which become more elongated, with pronounced nucleoli, and develop in many cases marked cytoplamsic vacuolation. Some cells show accumulations of lipid droplets. Interdigitations between adjacent cells become more complex, and the numbers of atrophic cells increase. The significance of the various cell conditions is considered. The ultrastructural appearances suggest that parathyroid gland cellular activity is stimulated in response to the drug-induced hypercorticoidism, but no overall glandular hypertrophy is found.