Long term effects of myochrysine in articular cartilage.

Intra-articularly administered sodium aurothiomalate (Myochrysine) produced aurosomes containing characteristic electron dense contents (indicating the presence of gold), in the chondrocytes of rabbit articular cartilage. At first the aurosomes were bounded by a membrane but later the electron dense contents were seen lying free in the cytoplasmic matrix. Such deposits were detectable up to 14 months after injection of Myochrysine but none were found at later time intervals (18 months and 2 years). There was a reduction in the population of superficial chondrocytes (Zone I) while those in deeper zones (Zones II and III) showed an increased content of intracytoplasmic filaments. It is thought that these are regressive or degenerative changes produced by gold.