[The structural reorganization of the calcium-regulating glands in body adaptation to high altitude].

The parathyroid cells and thyroid C-cells were studied morphologically, morphometrically and electron microscopically at the altitude of 3200 m. The increase of functional activity of both parathyroid cells and thyroid cells was observed starting from the 7th day of being at the high altitude. This was manifested in the increase of C-cell number, their size and ultrastructurally in the cell organelles hyperplasia and hypertrophy. As distinct from the normal altitude, high activity of the parathyroid cells was not compensated by an increased function of C-cells, this dysfunction resulting in a high blood level of calcium which may serve as a criterion of this hormonal system adaptivity and as an index of a new level of calcium homeostasis.