Pericellular matrix of growth plate chondrocytes: a study using postfixation with osmium-ferrocyanide

The pericellular matrix surrounding chondrocytes from all zones of epiphyseal growth plate cartilage, as well as from articular, tracheal, and auricular cartilage, was examined using a number of variations of osmium ferrocyanide postfixation of aldehyde-fixed tissues. Comparisons were made with other fixative techniques, including ruthenium red, safranin O, and lanthanum nitrate, all of which have previously been reported to stabilize a variety of lacunar matrix components. An electron-dense material was preserved uniquely by osmium-ferrocyanide in the lacunar matrix of mid and late zone hypertrophying chondrocytes and was absent from all other zones of the growth plate as well as from the other types of cartilage examined. Because of its highly restricted distribution, this electron-dense material is hypothesized to represent a pericellular matrix component involved with either matrix calcification or metaphyseal capillary penetration. Several hypotheses are presented as to its specific composition.