Light and electron microscopic observation on the process of tissue calcification in a case of parathyroid adenoma

Metastatic calcification in various organs in an autopsy case of parathyroid adenoma was studied by light and electron microscopy. Calcification was observed in kidney, lung, liver, heart, stomach, and thyroid. In the kidney, calcification was found in the tubules and glomeruli. In the liver, calcification was mainly found in Disse's space. The kidney, lung, liver, and heart were examined by electron microscopy. Four forms of early calcification were observed: 1) amorphous dense bodies within the mitochondria; 2) needle-shaped hydroxyapatite; 3) concentric laminated structure; and 4) cytoplasmic vesicles originating in hepatocytes. Calcium phosphate precipitates within the mitochondria were seen as amorphous dense bodies. When calcium phosphate precipitated in the cytoplasmic colloid gel, concentric laminated structures were formed due to Liesegang's phenomenon. Needle-shaped crystals in the amorphous dense bodies of the mitochondria were interpreted as a phenomenon of epitaxy. Calcification in Disse's space was thought to start in cytoplasmic vesicles which were derived from hepatocytes.