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Micro-morphology of pineal gland calcification in age-related neurodegenerative diseases.

BACKGROUND
The formation of concrements in human pineal gland (PG) is a physiological process and, according to many researchers, is associated with the involution of PG structures. The majority of scientific publications concern progressive calcification of pineal gland (PG), leaving out studies on the destruction of already formed calcified concrements. Our study fills the gap in knowledge about calcified zones destruction in PG in normal agind and neuropathological conditions, that hasn't been addressed until now.


PURPOSE
Our objective is to gain insight into human pineal gland (PG) tissue impairment in both normal aging and neurodegenerative conditions. X-ray phase contrast tomography (XPCT) allowed us to study PG tissue degeneration at high spatial resolution and, for the first time, to examine the damaged PG concrements in detail. Our research finding could potentially enhance understanding of the PG involvement in the process of aging as well as in Alzheimer's disease (AD) and vascular dementia (VD).


METHODS
The research was carried out on human PG autopsy material in normal aging, VD and AD conditions. Laboratory-based micro- computed tomography (micro-CT) was used to collect and evaluate samples of native, uncut, unstained PG with different degrees of pineal calcification. The detailed high-resolution 3D images of the selected PGs were produced using synchrotron-based X-ray phase contrast tomography (XPCT). Histology and immunohistochemistry of soft PG tissue confirmed XPCT results.


RESULTS
We performed via micro-CT the evaluation of the morphometric parameters of PG such as total sample volume, calcified concrements volume, and percentage of concrements in the total volume of the sample. XPCT imaging revealed high-resolution details of age-related PG alteration. In particular, we noted signs of moderate degradation of concrements in some PGs from elderly donors. In addition, our analysis revealed noticeable degenerative change in both concrements and soft tissue of PGs with neuropathology. In particular, we observed a hollow core and separated layers as well as deep ragged cracks in PG concrements of AD and VD samples. In parenchyma of some samples we detected wide pinealocyte-free fluid-filled areas adjacent to the calcified zones.


CONCLUSION
The present work provides the basis for future scientific research focused on the dynamic nature of PG calcium deposits and PG soft tissue in normal aging and neurodegenerative diseases. This article is protected by copyright. All rights reserved.