Figure 76

Photomicrograph of the proximal end of a growing long bone. A

disc of hyaline cartilage-the epiphyseal plate-separates the more proximally located epiphysis from the funnel-shaped diaphysis located distal to the plate. The articular cartilage on the surface of the epiphysis contributes to the synovial joint and is also composed of hyaline cartilage. Whereas the cartilage of the epiphyseal plate disappears when lengthwise growth of the bone is completed, the articular cartilage remains throughout life. The spaces within the bone are occupied by marrow. x85.

ducing new cartilage or in very slow growing cartilage. The changes that occur during the differentiation of new chondrocytes in growing cartilage are illustrated in Figure 7.3.

There are some exceptions to the general rule that hyaline cartilage is surrounded by a perichondrium. These include areas where cartilage forms a free surface, as in the articular surfaces in joints, and areas where cartilage makes direct contact with bone, as in the nasal and costal cartilages and sites of bone formation. In these areas, proliferation of chondrocytes within the cartilage lacunae provides the new cells for interstitial growth.

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