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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;

Histology

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

References