The sites of hormone storage in normal and diseased parathyroid glands: a silver impregnation and immunohistochemical study

The results of Grimelius' silver impregnation method and of two immunohistochemical methods for the demonstration of the sites of storage of parathyroid hormone (PTH) were compared in a series of parathyroid glands from 39 patients affected by either hyperplasia or adenoma and from 10 normal subjects. An indirect immunoperoxidase method using an anti-bovine PTH serum gave unsatisfactory results. In contrast a biotin-streptavidin immunoperoxidase method using an antibody against the 44-68 amino acid sequence of human PTH yielded similar results to those with Grimelius' silver impregnation method. This supports the view that argyrophil granules correspond to the secretory granules of PTH. The degree of silver impregnation, however, varied considerably in duplicate sections, probably because of difficulties in standardization of the Grimelius' method. The biotin-streptavidin method appeared more sensitive and was reproducible. The immunohistochemical demonstration of PTH may prove useful in defining the sites of hormone storage in normal and pathological conditions.