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Cartilage: - it is composed of cells, chondrocytes, fibers, and a gel-like ground substance. Cartilage is an avascular, aneural, and alymphatic tissue.
There are three types of cartilages:-Hyaline, Elastic and Fibro cartilages
Cell types of cartilage
1. Chondroblasts: oval-shaped with a spherical nucleus and prominent Golgi and rER.
2. Chondrocytes: The chondroblasts, when they get trapped in a lacuna, are called chondrocytes. They are less active. They vary in shape from elongated to spherical. They have a spherical nucleus, a Golgi apparatus, and rER. Glycogen and lipid droplets can accumulate in the older cells.
3. Chondroclasts: are multinucleated giant cells resulting from fusion of macrophages and are cartilage-eating cells.
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Hyliane cartilage:
- It has a white, glassy appearance (Greek word hyalos, meaning ‘glass’).
- It is found on the articulating surface of bones and provides support in the nose, larynx, trachea, and bronchi
- The ground substance contains type II collagen fibres, which have the same refractive index as the ground substance, so they can’t be seen in routine staining.
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Elastic Cartilage: It is found in the parts where elasticity, along with rigidity, is required. E.g., external ear, epiglottis, external auditory canal, corniculate and cuneiform cartilages of the larynx.
This cartilage contains a dense network of elastic fibres along with other constituents of cartilage
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Fibrocartilage occurs least frequently.
- It is found in intervertebral disks and menisci of stifle joint.
- The most striking feature is the presence of an abundance of collagen I in the matrix in parallel or V-shaped orientation (Herringbone pattern).
- It lacks a distinct perichondrium. This type is intermediate between the cartilage and dense irregular c.t.
