The parathyroid gland in metal rickets. A stereological study

Rickets can be induced by oral administration of metals. A depressive effect exerted by metal ions on the parathyroid gland has previously been suggested to be a pathogenetic factor in strontium-induced rickets. In the present investigation, rickets was induced in young rats by oral administration of strontium and manganese, respectively. The parathyroids were fixed by perfusion and the total volume of the parathyroid glands was determined by serial sectioning. Conventional stereological techniques were applied on the ultrastructural level and the densities obtained could be related to the total mass of parathyroid tissue. In both rachitic groups the volume of the parathyroid glands as well as the absolute amounts of all cellular components studied, were reduced. All these changes were, however, correlated to the decreased body weight of the experimental animals. This is well in line with the finding of unaltered serum concentrations of calcium and immunoreactive parathyroid hormone. Therefore, it is concluded that the parathyroids do not play an important role in the pathogenesis of metal rickets.