Elastic Cartilage

Elastic cartilage is a type of cartilage which has abundant elastic fibers in the matrix. It is more elastic and flexible than hyaline cartilage. It is found in the pinna (auricle) of the external ear, the walls of the external auditory meatus, the Eustachian tube, the epiglottis, and part of the larynx.

Histology

In the light microscope, untreated elastic cartilage looks similar to hyaline cartilage. However, special stains reveal that elastic cartilage contains elastic fibers, which is composed of elastin and collagen fibers. The extracellular matrix is metachromatic due to high concentrations of glycosaminoglycans. Elastic cartilage elasticity ensures the patency (aperture/dilation) of the lumina (diameter) of tubes that are surrounded by this variety of cartilage.

Elastic cartilage is very resilient and is adapted mainly to withstand repetitive bending. It supports the epiglottis and external ear, which are required to be flexible and capable of springing back when bent. It resembles hyaline cartilage, except that in addition to its content of type II collagen fibrils, the matrix contains acidophilic elastic fibers. The chondroblasts that produce the various matrix constituents (including the elastin) become embedded in matrix as chondrocytes.

Below, light micograph of elastic cartilage from the epiglottis. The arrows indicate the darkly stained elastic fibers.