CartilageCartilage is a translucent, elastic tissue. Cartilage contains no vessels, and consists of a homogeneous, intercellular matrix, in which there are numerous minute cavities, or capsules, containing protoplasmic cells. Cartilage in meat is called gristle,Unlike bone, native cartilage has little or no capacity to regenerate. Because cartilage has no vascular supply, it lacks the rich source of progenitor cells and growth factors needed for tissue regeneration. Unless a defect is quite small, in which case it can self-repair, cartilage cannot repair itself. Bioengineering techniques are being developed to generate new cartilage, using a cellular "scaffolding" material and cultured cells to grow artificial cartilage.
Cartilage is found in various parts of the human body —- in adult life chiefly in the joints, in the parietes of the thorax, and in various tubes, such as the trachea and bronchi, nose, and ears, which require to be kept permanently open. In the fetus, at an early period, the greater part of the skeleton is cartilaginous; as this cartilage is afterward replaced by bone, it is called temporary, in contradistinction to that which remains unossified during the whole of life, and is called permanent.
Cartilage is divided, according to its minute structure, into hyaline cartilage, white fibrocartilage, and yellow or elastic fibrocartilage.
Hyaline cartilage consists of a gristly mass of a firm consistence, but of considerable elasticity and pearly bluish color. Except where it coats the articular ends of bones, it is covered externally by a fibrous membrane, the perichondrium, from the vessels of which it imbibes its nutritive fluids, being itself destitute of bloodvessels. It contains no nerves. Its intimate structure is very simple. If a thin slice is examined under the microscope, it will be found to consist of cells of a rounded or bluntly angular form, lying in groups of two or more in a granular or almost homogeneous matrix. The cells, when arranged in groups of two or more, have generally straight outlines where they are in contact.
It has been said that the cartilage in ears and noses continues to grow in size throughout adult life; however, this seems to be an urban myth which is not substantiated by research.
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