Histology - Cartilage
Three Cartilage Types
Hyaline, elastic, and fibrocartilage
- Cartilage type is determined by matrix and fiber components.
Hylaine Cartilage
The most common type in the body.
Matrix
- Glassy, pink-staining, gel-like matrix comprises a ground substance of proteoglycan aggregates, chondronectin, and water.
Isogenous groups of chondrocytes are housed within lacunae; the darker staining ring around the lacuna is the cartilage capsule.
Invisible type II collagen fibers.
Locations:
- Sternal ends of the ribs, many articular surfaces, the tracheal rings, the larynx, and the nasal septum.
- Hyaline cartilage is also the skeletal precursor during development.
Functions:
- At the articular surfaces, hyaline cartilage provides a smooth surface for free movement; elsewhere, such as in the nasal septum, it provides structural support.
Elastic Cartilage
Shares many similarities with hyaline cartilage.
Matrix
- Very light staining
Chondrocytes in lacunae
Elastic fibers create a dark-staining network around the lacunae
Locations:
- Auditory tubes, epiglottis, and external ear
Functions
- Elastic fibers provide flexibility with recoil; for example, when you bend your external ear, it moves easily, but snaps back into place when released.
Fibrocartilage (aka, fibrous cartilage)
Highly organized appearance.
Collagen fibers
- Tightly packed, thick bundles of type I and type II collagen fibers run in parallel.
Lacunae and chondrocytes lie in rows between the collagen bundles.
Locations
- Intervertebral discs, the pubic symphysis, and the joint capsules
Functions:
- Provides tensile strength and resistance to compression; its dense nature allows it to bear a weight, as in the intervertebral discs.