Vitamin A uptake cells in the endocrine organs of Japanese quails, Coturnix coturnix japonica

The vitamin A uptake cells in the anterior pituitary, thyroid gland, and pancreas of Japanese quails, coturnix coturnix japonica, were examined by the use of Sudan III staining, toluidine blue staining, fluorescence microscopy and electron microscopy. After excess vitamin A administration, most of interstitial cells, corresponding to fibroblasts, increased markedly the size and number of lipid droplets in the cytoplasm which emitted vitamin A fluorescence intensively. The reactions to vitamin A administration were in parallel with the vitamin A dosage. In particular, the cells of the thyroid gland and pancreas were comparable to the Ito cells of the liver in their vitamin A uptake capacity. The present study demonstrates that interstitial cells either identical with or closely related to the Ito cells of the liver are widely distributed in the connective tissue of these endocrine organs. The possible physiological roles of the vitamin A uptake cells and also the species difference in the vitamin A uptake capacity of these cells are discussed.