Humps on young human and rabbit articular cartilage.

Scanning electron microscopic studies revealed numerous humps on the surface or articular cartilage from a 7 years old boy and from 1 month old rabbits. This shows that the surface topography of articular cartilage in young individuals is different from that of older individuals (human and rabbit) where the surface is beset by numerous pits. In 2 months old rabbits an intermediate situation was witnessed, for both shallow pits and occasional humps were present. Ridges and undulations were not seen on the articular surface of the 7 years old boy, except near the cut edge of the specimen. They were, however, found on air-dried specimens of 1 month old rabbit cartilage, but were absent from specimens dried by the critical-point method. The collective evidence supports the idea that ridges and undulations are not a constant feature of the normal articular surface, but that such features are artefactual, a typical or pathological.