Ultrastructural change in the parathyroid gland of the phosphate treated newt, Triturus pyrrhogaster (Boié).

thyroid glands of the phosphate treated and hibernating (control) newts. The parenchymal cells of the newt parathyroid gland were classified into basal cells and suprabasal cells. Daily administration of phosphate caused no marked changes in the former cells. In the latter under experimental conditions, granular and agranular endoplasmic reticula and small dense granules seemed to be increased in number, while glycogen granules appeared decreased in number when contrasted to those in the control newts. The Golgi apparatus and large homogeneously dense bodies were increased in number reaching a maximum after 7 days of phosphate administration, and lipofuscin-like bodies were gradually increased in number during the experimental stages. On the contrary, vacuolar bodies were first rapidly, then gradually decreased in number. Large heterogeneously dense bodies subdivided into a vesicular type and lysosomal type were slightly decreased during 14 days' administration of phosphate and increased in number after 21 day administration. Under experimental conditions the vesicular type heterogeneously dense bodies were more dominant than the lysosomal type. The numbers of mitochondria were hardly varied as compared with control newts. From the above results it is conceivable that alterations in cell organelles and inclusion bodies indicate hyperfunction of the suprabasal cell caused by phosphate administration. However, mutual correlations of inclusion bodies remain incompletely clarified.