This is a demonstration of local traumatization of articular cartilage inducing mitoses in parts of a joint other than the site of inquiry. Parts of one of the patellar cartilages of the full-grown rabbit were scored while the other knee was subjected only to arthrotomy. Radioactive thymidine and autoradiographic technique demonstrated that labeled chondrocytes appeared not only around the score in the patella but also scattered in the tibia and femoral condyles. Whether the mechanism of regional mitotic stimulation is a reduction of the concentration of the normal cell specific inhibitors of mitosis, or so-called chalones is not known and requires further investigation.

Animals↗

PubMedDate not supplied

The effect of growth hormone and thyroxine on adult joint cartilage.

In adult rabbits, four longitudinal scores (knife cuts) were surgically produced in articular cartilage of the right patella. Post-operatively, they were treated with growth hormone or thyroxine. Histologically degeneration, relatively undiminished orthocromasia, and metachromasia were seen around the scores. In the scores, chondrocytes labeled with 3H-thymidine were seen scattered around the joint. This labeling was more pronounced in the hormone-treated than in the control groups. In the control left knees, almost all joints contained labeled cartilage cells, especially in the hormone-treated groups. In rabbits not operated on, but treated with the same doses of the two hormones, 19 of 20 knee joints contained labeled chondrocytes, whereas no signs of degeneration of the cartilage could be seen. Mitosis of chondrocytes is normally not found in adult articular cartilage and it is evident that the two hormones in some way act as a stimulator of mitotic division.

Animals↗

PubMedDate not supplied

Mitosis of chondrocytes in normal adult joint cartilage.

Local traumatization of adult rabbit joint cartilage induces mitosis of chondrocytes not only in the cartilage of traumatized joints but also of the normal cartilage of sham-operated or unoperated-on control joints. All the cartilage of the patella groove of the femur of adult rabbits was excised while the other knee underwent arthrotomy or was left intact. Radioactive thymidine and autoradiographic technique demonstrated that labeled chondrocytes appeared not only around the excised cartilage but also scattered in the tibia and femoral condyles. Scattered mitoses of chondrocytes were also seen in the normal cartilage of sham-operated and unoperated-on control knee joints. The peak of labeling appeared two weeks after operation, and the operation did not result in development of osteoarthritis. Whether the stimulation of chondrocytes is due to a decrease in cell-growth-inhibiting factor or to a liberation of stimulating substances is not known.

Animals↗

PubMedDate not supplied

Morphology and crystal composition of chondrocalcinosis after osteochondritis dissecans.

Three patients, who in their youth had been operated upon for osteochondritis dissecans in the femoral condyles, and who had developed gonarthrosis and chondrocalcinosis 30 years later, were investigated by arthrotomy. Tissue was obtained from the semilunar cartilages, the joint cartilages and the synovialis, for crystal analysis and morphological studies. The calcium deposits were with X-ray diffraction and polarization microscopy, The compound found was mainly calcium pyrophosphate dihydrate. Crystals were seen in all the tissues studies and the deposits could also be seen in micro-radiography. The histological examination demonstrated mainly degenerative, but also regenerative changes in the articular cartilage. On the site of the osteochondritis lesion the fibrous tissue was very rich in crystals. In the semilunar cartilages and the synovialis crystals were also seen.

Adult↗