Studies on the clearance of calcium pyrophosphate crystals from facsimile synovium.

Calcium pyrophosphate dihydrate crystals have been injected into the air pouch model of facsimile synovium. At various time intervals after crystal injection both infiltrating exudate cells and lining tissue were examined for the presence of crystalline material. The results show that the crystals are initially engulfed by mononuclear cells and to a lesser extent by polymorphonuclear cells in the exudate. Later, crystals became embedded in the lining tissue either within mononuclear cells or as crystal masses confined within granulomas. These studies suggest that the mesenchymal cells ( facsimile synovium) lining rat air pouches can clear calcium pyrophosphate dihydrate crystals from the air pouch cavity. It is therefore inferred that crystals found in the lining of human joint synovium may be incorporated therein by a similar mechanism.