Pineal calcification: its mechanism and significance.
On the basis of conventional transmission electron microscopy and ultracytochemical reactions for demonstration of calcium, for glucose-6-phosphatase, and for Ca2+-ATPase, intracellular and extracellular mineralization foci in the superficial pineal gland of the Mongolian gerbil (Meriones unguiculatus) have been described. The initial intracellular calcification sites occur in the cytoplasmic matrix, vacuoles, mitochondria and the endoplasmic reticulum of large clear pinealocytes. These loci, and particularly those within the cytoplasmic matrix, transform into acervuli by a further addition of hydroxyapatite crystals. The cells gradually degenerate, die, break down, and the acervuli reach the extracellular space. It has been suggested that the reason for a rise in intracellular calcium levels could be the incapacity of Ca2+-ATPase to eliminate this cation from the cell, so that the hypercalcemic intracellular milieu becomes favourable for the initial crystallization. The primary extracellular mineralization sites occur in the calcium-rich flocculent material. The mineralization process in the gerbil pineal gland is interpreted as a histophysiological phenomenon intimately related to the metabolic activity of the pineal gland.
D000818:Animals; D002113:Calcification, Physiologic; D002118:Calcium / Q000032:analysis*; D000252:Calcium-Transporting ATPases / Q000032:analysis; D017886:Durapatite; D005260:Female; D005849:Gerbillinae; D006882:Hydroxyapatites / Q000032:analysis; D008297:Male; D008854:Microscopy, Electron; D010870:Pineal Gland / Q000201:enzymology / Q000648:ultrastructure*; D014617:Vacuoles / Q000648:ultrastructure
D006882:Hydroxyapatites; D017886:Durapatite; D000252:Calcium-Transporting ATPases; D002118:Calcium