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Hyaline cartilage



- Discussion:
    - hyaline cartilage is the most common variety of cartilage;
    - it is found in costal cartilages, articular cartilages, epiphyseal plates, & majority of fetal skeleton that is later replaced by bone;
    - chondrocytes, occupy lacunae generously distributed through the matrix;
          - each peripheral lacuna typically houses a single chondrocyte;
          - deeper lacunae may contain two or more chondrocytes;
          - surrounding each cell is a territorial matrix w/ a higher concentration of proteoglycans;
    - free surfaces of most hyaline cartilage (but not articular cartilage) are covered by a layer of fibrous connective tissue, perichondrium;
          - deep portion of perichondrium is composed of chondroblasts;
          - external portion is less cellular and more densely fibrous;
    - approx 10% of wet weight of cartilage is collagen;
    - approx 75% of matrix is water;
    - remainder is a nonfibrous filler material;
    - these entities together form stiff sol;
    - cartilage contains predominantly type II collagens w/ lesser amounts of type IX and type XI;
    - functions of collagen fibers w/ in cartilage:
          - provides tensile strength to the tissue and resist movement of interstitial water & proteoglycans from the cartilage, esp. while it 
                sustains compressional loading;
          - to anchor ground substance of articular cartilage to subchondral bone;
    - filler material of cartilage is composed of proteoglycan aggregates w/ chondroitin sulfate & keratan sulfate as chief glycosaminoglycans;
   - much of hyaline cartilage of the body ultimately calcifies w/ maturation;
          - when calcification occurs, chondrocytes die & matrix disintegrates;
          - articular cartilage is unique in that its more superficial zones do not calcify, except in pathologic states such as pseudogout

- Histology:
    - young chondrocytes & chondroblasts have rounded nuclei (or double nuclei);
    - cytoplasm contains elongated mitochondria, well-developed Golgi apparatus, varying amounts of glycogen, & lipid droplets



Medical Progress: Epiphyseal Disorders.

The deleterious effects of drying on articular cartilage.

The viability of articular cartilage in fresh osteochondral allografts after clinical transplantation.

The effects of exposure of articular cartilage to air. A histochemical and ultrastructural investigation.

The potential for regeneration of articular cartilage in defects created by chondral shaving and subchondral abrasion. An experimental investigation in rabbits.

The induction of neochondrogenesis in free intra-articular periosteal autografts under the influence of continuous passive motion. An experimental investigation in the rabbit.



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Friday, June 1, 2012 9:44 am