|Hyaline cartilage showing microanatomy of chondrocytes and organelles, lacunae and matrix.|
Hyaline cartilage is a type of cartilage found on many joint surfaces. It is pearly bluish in color with firm consistency and has a considerable amount of collagen. It contains no nerves or blood vessels, and its structure is relatively simple.
Hyaline cartilage is covered externally by a fibrous membrane, called the perichondrium, except at the articular ends of bones and also where it is found directly under the skin, i.e. ears and nose. This membrane contains vessels that provide the cartilage with nutrition.
If a thin slice is examined under the microscope, it will be found to consist of cells (chondrocytes) of a rounded or bluntly angular form, lying in groups of two or more in a granular or almost homogeneous matrix. Chondrocytes are cartilage cells that produce the matrix. When arranged in groups of two or more, chondrocytes have generally straight outlines where they are in contact with each other, and in the rest of their circumference are rounded. They consist of clear translucent protoplasm in which fine interlacing filaments and minute granules are sometimes present; embedded in this are one or two round nuclei, having the usual intranuclear network.
The cells are contained in cavities in the matrix, called cartilage lacunae; these are actually artificial gaps formed by the shrinking of the cells during the staining and setting of the tissue for observation. The interterritorial space between the isogenous cell groups contains relatively more collagen fibers, causing it to maintain its shape while the actual cells shrink, creating the lacunae. This constitutes the so-called capsule of the space. Each lacuna is generally occupied by a single cell, but during the division of the cells it may contain two, four, or eight cells.
Hyaline cartilage exists on the ventral ends of ribs; in the larynx, trachea, and bronchi; and on the articular surface of bones.
Though it is often found in close contact with menisci and articular disks, articular cartilage is not considered a part of either of these structures, which are made entirely of fibrocartilage. Not covered by synovial membrane.
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