Histological and immunohistological studies on cartilage.

The material properties of dense avascular connective tissues such as cartilage present unique challenges to the development of any prospective histological procedures. This chapter documents some of the protocols we have developed in our laboratories for the histological and immunohistochemical evaluation of extracellular-matrix components in normal and pathological articular cartilage. Illustrative examples are provided of specimens from an ovine meniscectomy model of osteoarthritis. A major strength of this experimental animal model is that spatial and temporal changes in joint matrix components can be followed longitudinally in an animal population of well-defined pedigree that minimizes biological variation. Furthermore, a systematic experimental approach can be adopted with this model using cartilage specimens from early predegenerative stages to later advanced stages of joint degeneration. Significantly, the histological changes observed in this model closely parallel changes evident in joint tissues during osteoarthritis in humans and have provided significant insights into these degenerative processes.