The normal parathyroid glands of the Mongolian gerbil. A quantitative structural study.

The parathyroid glands of the normal Mongolian gerbil were studied by light and electron microscopy, using stereology and semi-automatic image analysis. Basic quantitative data are presented for various nuclear parameters, and for mitochondria, endoplasmic reticulum, Golgi complex, secretory granules, storage granules, lysosomes and lipoid bodies. Chief cells predominate in the normal gland. Atrophic cells are only rarely encountered. The chief cells can be qualitatively subclassified into light, dark and intermediate variants, but quantitatively there is no difference among these variants with regard to the volume densities of mitochondria, lamellar rough endoplasmic reticulum, Golgi complex, secretory granules and storage granules, suggesting that the subclassification of the chief cells plays no functional role. A statistically significant correlation between volume densities of Golgi complex and secretory granules was found. Compared with the chief cells, the atrophic cells exhibit significantly less lamellar rough endoplasmic reticulum and secretory granules, whereas the content of vesicular rough endoplasmic reticulum is increased. The atrophic cells are suggested to be a degenerative variant of the chief cells.