Cartilaginous bone extremities of growing monotremes appear unique

✍ Scribed by Thorp, B. H. ;Dixon, J. M.

• Book ID: 102744403
• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 885 KB
• Volume: 229
• Category: Article
• ISSN: 0003-276X
• DOI: 10.1002/ar.1092290403

✦ Synopsis

Cartilage canals are present in the epiphyseal cartilage of most mammals and birds. They are considered necessary for the maintenance of chondrocytes and for the formation of epiphyseal ossification centers. The epiphyseal cartilage of marsupials was recently shown not to contain cartilage canals, and placental rats appear not to have cartilage canals, although some confusion exists in the literature. The present study examines the cartilaginous epiphyses and physes from the knee and hip of the rat and the two Australian monotremes (platypus, Ornithorhynchus anatinus and echidna, Tachyglossus aculeatus). In all three species, cartilage canals were absent. Vessels to epiphyseal ossification centers were present, however. In the center of the cartilaginous femoral head of the echidna, but not in the platypus or rat, there was a large cauity, which contained connective tissue and was lined by a n endochondrium of chondroproginator cells. These appeared to be contributing to growth of the cartilaginous epiphysis. No