[Recrystallization and reaction of urates in gout tophus after fixation with glutaraldehyde]

Uric acid and urates usually dissolve in the instance of routine fixation of material with formol. Bioptic confirmation of diagnosis is therefore usually very difficult if a murexide reaction test cannot be carried out concurrently. After fixation in glutaraldehyde for electron optic aims the crystals remain present in microscopic paraffin preparations for a long period of time and undergo even recrystallization which largely facilitates the microscopic diagnosis. It is assumed that a compound of the urates and diglutaraldehyde develops. It has been shown electron-optically that the crystals deposit for the most part in connective tissue or in the basic mass of cartilage without close relation to the cell elements. Underlying tissue is afflicted by necrosis, adjacent tissues show abundant fibroblasts which have however no closer contact with the crystals.