CELL AND MATRIX CHANGES ASSOCIATED WITH PATHOLOGICAL CALCIFICATION OFTHE HUMAN ROTATOR CUFF TENDONS

The causative mechanism of tendon calcification ('calcifying tendiniti s') is unknown. In this report, pathological human tendon samples were examined to give morphological and ultrastructural detail of the calc ified regions and these findings were compared with those from normal tendon. Selected specimens were cryosectioned to enable histochemical and immunohistochemical comparison of the occurrence and distribution of specific matrix molecules in diseased and normal tendon tissues. Th e lack of collagen type II and alkaline phosphatase in the pathologica l regions suggests that the calcification process is not mediated thro ugh an endochondral transition. In contrast, the pathological areas we re characterised by widespread labelling for chondroitin-4-sulphate/de rmatan sulphate and intense pericellular localisation of chondroitin-6 -sulphate.