Crystal-matrix interrelations in brushite and uric acid calculi

Area of Science:

• Biomineralization
• Materials Science
• Urology

Background:

• Understanding the structural composition of urinary calculi is crucial for developing effective treatments.
• The role of the organic matrix in stone formation is not fully elucidated.

Purpose of the Study:

• To investigate the microstructural organization of brushite and uric acid calculi.
• To determine the relationship between the organic matrix and crystal formation in these calculi.

Main Methods:

• Scanning electron microscopy (SEM) with partial dissolution.
• Transmission electron microscopy (TEM).

Main Results:

• Brushite calculi exhibit radially oriented columnar crystals with a sheet-like substructure, and the organic matrix is found both externally and internally.
• Uric acid calculi also display radially oriented crystals with incorporated matrix forming a fine meshwork.
• Concentric matrix bands are observed, with varying densities and orientations relative to crystal lattices.

Conclusions:

• The organic matrix in these calculi likely originates from a mucinous surface coat.
• Crystal growth occurs within this gel-state matrix, leading to its incorporation or displacement.
• These findings provide insights into the pathogenesis of urinary stone formation.