Corpora arenacea (singular: corpus arenaceum,[1] also called brain sand or acervuli[2][3] or psammoma bodies[4] or pineal concretions[4]) are calcified structures in the pineal gland and other areas of the brain such as the choroid plexus. Older organisms have numerous corpora arenacea, whose function, if any, is unknown. Concentrations of "brain sand" increase with age, so the pineal gland becomes increasingly visible on X-rays over time, usually by the third or fourth decade. They are sometimes used as anatomical landmarks in radiological examinations.[5]
^Angervall, Lennart; Berger, Sven; Röckert, Hans (2009). "A Microradiographic and X-Ray Crystallographic Study of Calcium in the Pineal Body and in Intracranial Tumours". Acta Pathologica et Microbiologica Scandinavica. 44 (2): 113–119. doi:10.1111/j.1699-0463.1958.tb01060.x. PMID13594470.
^Bocchi, Giancarlo; Valdre, Giovanni; Valdre, Giovanni (1993). "Physical, chemical, and mineralogical characterization of carbonate-hydroxyapatite concretions of the human pineal gland". Journal of Inorganic Biochemistry. 49 (3): 209–20. doi:10.1016/0162-0134(93)80006-U. PMID8381851.
^Baconnier, Simon; Lang, Sidney B.; Polomska, Maria; Hilczer, Bozena; Berkovic, Garry; Meshulam, Guilia (2002). "Calcite microcrystals in the pineal gland of the human brain: First physical and chemical studies". Bioelectromagnetics. 23 (7): 488–95. doi:10.1002/bem.10053. PMID12224052. S2CID13276067.