Proteoglycan association with collagen d band in hyaline articular cartilage

Proteoglycans of canine articular cartilage were labelled for transmission electron microscopy using the cationic copper phthalocyanin dye, cupromeronic blue, in a critical electrolyte concentration method. Much of the proteoglycan appeared to be structurally unrelated to collagen but a small proportion was positioned close to fibrils. On demonstrating the characteristic collagen banding pattern with uranyl acetate and phosphotungstic acid, it was evident that proteoglycan interacted with collagen at the d band.