“…9.5), have shown that enzyme activity first appears on the membrane of osteoblasts and chondrocytes and, as globule-like precipitates, around and outside the cell membrane of lower maturing chondrocytes and hypertrophic chondrocytes (Morris et al 1986;Akisaka and Gay 1985b;Bianco 1990). 9.5, inset) (de Bernard et al 1986;Morris et al 1986Morris et al , 1992aBianco 1990;Masuhara et al 1992) and by the presence of alkaline phosphatase activity in isolated matrix vesicles (Ali et al 1970(Ali et al , 1971Majeska and Wuthier 1975;Fortuna et al 1978;Kahn et al 1978;Väänänen and Korhonen 1980;Watkins et al 1980). These results were confirmed by alkaline phosphatase immunohistochemistry ( Fig.…”