The localization of articular cartilage proteoglycan by electron microscopy

Rabbit articular cartilage was fixed with glutaraldehyde containing Ruthenium Red or Safranin O to localize proteoglycan. By light and electron microscopy, Safranin O proteoglycan localization is easily obtained. Ruthenium Red stained proteoglycan is easily visualized by electron microscopy. Previous digestion with papain prevented staining by either technique confirming that the material was indeed proteoglycan. Using these methods of proteoglycan identification the sites of attachment to collagen are shown as well as the deposition of proteoglycan about cells of differing vitality and the relationship of proteoglycan to cell membranes.