Localization of tritiated vitamin A in lymph nodes of the mouse: an autoradiographic study of vitamin A-storing cells.

Localization of tritiated vitamin A in lymph nodes of the mouse was investigated by the use of light- and electron-microscopic autoradiography. Young male mice were fed a diet containing 3H-vitamin A acetate for a week. Lymph nodes were removed and prepared for autoradiography. Lipid droplets in fibroblast-like cells showed high concentrations of radioactivity. These cells were distributed around lymphatic sinuses and blood vessels. The cells can, therefore, be classified as "vitamin A-storing cells" according to criteria proposed earlier by Yamada and Hirosawa (1976). Control animals from the same litter were maintained on ordinary laboratory food for the same period and examined by electron microscopy. Lipid-droplet-containing cells were found in the same areas as in the experimental animals but in fewer numbers. This suggests that the increased number of vitamin A-containing lipid droplets is due to hypervitaminosis A in the experimental animals. The presence of some cells containing these droplets in the control animals would imply that even under normal feeding conditions the animals ingested excess amounts of vitamin A, which was retained in lipid droplets. The stored vitamin A probably participates in metabolic processes such as the formation of glycoproteins in ground substance.