A possible role of collagen fibrils in the process of calcification observed in the capsule of the pineal gland in aging rats

Abstract

The relationship between collagen fibrils and calcified concretions exclusively appearing in the pineal gland of adult/aging rats has been investigated. Deposits of lanthanum, which replace calcium ions are distributed along collagen fibrils with a repeating period of about 70 nm. Calcium has been detected histochemically between collagen bundles surrounding extracellular concretions by means of the pyroantimonate method and by X-ray microanalysis. It is associated with phosphorus. The data presented here suggest that collagen fibrils are involved in the genesis and growth of extracellular concretions located in the connective tissue surrounding the pineal gland of aging rats.

Fibrous Calcareous Concretions in the Capsules of Human Pineal Glands

“…That is, the concretions showing a brown to blackish-brown color might be rich in organic components and the translucent-rich concretions might be more mineralized. The pineal capsule concretions showing high to lower BSE signals were calcified with Ca and P as were the pineal matrix concretions in adult humans 4-6, 9, 10 and aging rats 3 , and the capsule concretions in aging rats 12 . From the Ca / P molar ratios measured in this study Our comparison of concretions revealed a significantly higher P content in the matrix concretions compared to the capsule concretions in both the central and peripheral regions, although there was no significant difference in Ca content.…”

“…The characteristic structure of calcareous concretions was also observed in the connective tissue capsule of the pineal gland in aging rats by transmission electron microscopy 12 . However, such structures or their components remain to be identified in humans, although the presence of concretions in the pineal capsule was reportedly observed by optical microscopy 5,8 .…”

Mineralized Blood Vessels in the Capsules of Human Pineal Glands

“…However, the three-dimensional BSE images of blood vessels taken in this study showed the position of the mineralized deposits generally consistent with the circular arrangement of smooth muscle cells in the media walls. In addition, the smooth muscle cells of aortic 14 or arterial walls 15 are calcified in several diseases as well as the collagen fibers of connective tissues 11,[16][17][18] and the collagen and elastic fibers of aortic or arterial walls 18 .…”

“…Transverse planes of the vascular lumens showing mineralized deposits in this study resembled the capsular concretions with their rough concentric laminations. The peripheral substances might be smooth muscle cells, collagen and elastic fibers, and / or amorphous organic plaques that have been mineralized 11,[16][17][18] , whereas the blood vessel lumens filled with mineralized deposits may result from the calcification of organic contents such as plaque when a patient is affected by atherosclerosis or thrombosis [21][22][23][24] . Regrettably, we could not determine a clear relationship between the MSD showing a hyper-mineralization and the smaller mineralized round-shaped deposits attached to the blood vessels, as shown in Fig.…”

“…These pineal glands also contained mineralized blood vessels as seen in Fahr s disease 15 , and many capsular concretions. Therefore, in a human pineal gland susceptible to mineralization, a process is most likely to occur in the connective tissue capsule [12][13][14][15][16] of the gland as well as in the matrix 11,12,14 .…”