Electron microscopic investigations on aging and osteoarthrotic human articular cartilage

Summary The submicroscopic morphology of freeze-etched aging human articular cartilage is reported. In contrast to chemically fixed and thin sectioned cartilage tissue, chondrocytes and matrix of freeze-etched specimens exhibit new morphological aspects.The surface of superficial chondrooytes shows invaginations and bulges, producing a cauliflower-like appearance of the cell body. Finger-like protrusions as found in thin sections are absent. The matrix adjacent to the pericellular halo, the latter consisting of a fine granular material, is characterized by the presence of globular, membrane-bounded vesicles of variable size. This vesicle containing zone is called corona. The corona vesicles as well as the cellular membranes are occupied by two types of particles (85 and 135 Å in diameter). Based on the presence of these particles, the nature and possible origin of the corona vesicles are discussed.