Parathyroid morphology in gerbils after thyroidectomy and calcium administration.

Morphological studies of the parathyroid glands from adult Mongolian gerbils in which hypercalcaemia had been induced by thyroidectomy and calcium injections for 2-19 days were carried out. The potassium pyro-antimonate technique and subsequent X-ray analysis of the precipitates were used for ultrastructural localization of cations. Ultrastructurally, most (suppressed) chief cells exhibited a dense cytoplasm, medium-sized or large mitochondria, glycogen particles, inconspicuous endoplasmic reticulum and Golgi complex, calcium-containing precipitates mainly in mitochondria and nuclei, and sometimes also lysosomal bodies and accumulations of secretory granules which occasionally seemed to be discharged into cytoplasmic vacuoles. A few parenchymal cells showed a low cytoplasmic density, few organelles, and structurally altered mitochondria, occasionally with associated smooth-surfaced vacuoles. These cells possessed calcium-containing precipitates in mitochondria, smooth-surfaced vacuoles, and also diffusely in the cytosol. It is concluded, that, in the main part of the parenchymal cells, the hypercalcaemia had resulted in a suppression primarily of the synthetic and later also of the secretory activity, and that the calcium-containing precipitation is different in the chief cell variants.