Fig. 4

Micrographs were obtained using scanning electron microscopy SEM and histology. a The interface after cartilage removal from the subchondral bone plate using oxidation (scale bar 1000 μm). All collagen has been removed and the hydroxyapatite particles and canals formed by the cartilage are apparent. b The upper surface of the calcified cartilage zone after hyaline cartilage separation by ultrasonic shaking (scale bar 500 μm). Three-dimensional micrographs were reconstructed using digital microscopy. Micrographs were obtained using SEM. Collagen fibers separated from the bone plate could be observed. c Sectional view of the bone and cartilage without removing the cartilage from the bone. d Enlargement of 4C. The imbedding structure could be observed. e Sectional view of the bone after removing the cartilage. Arrows show the connection between bone and cartilage. Histological micrographs of Masson trichrome staining (f) and Safranin O/Fast Green staining (g) show the transitional structures between the subchondral bone and the cartilage (scale bar 200 μm): interlocking, defect, and imbedding