Cartilage

The three types of cartilage

There are three types of cartilage:

Hyaline - most common, found in the ribs, nose, larynx,

trachea. Is a precursor of bone.

Fibro- is found in in vertebral discs, joint capsules,

ligaments.

Elastic - is found in the external ear, epiglottis and larynx.

Hyaline cartilage:

This is a diagram of hyaline cartilage, showing active

chondrocytes sitting in their lacunae.

This type of cartilage has a glassy appearance when fresh, hence

its name, as hyalos is Greek for glassy. It looks slightly

basophilic overall in H&E sections.

Hyaline cartilage has widely

dispersed fine collagen fibers (type

II), which strengthen it. The collagen

fibers are hard to see in sections. It

has a perichondrium, and it is the

weakest of the three types of cartilage.

Look at the e. microscope of a section of cartilage on the left.

Make sure you can identify chondrocytes, the lacunae, matrix

and perichondrium.

Fibro cartilage:

This is a section of an in

vertebral disc, which

contains a layer of fibro

cartilage.

Identify the chondrocytes in

lacunae, and thick bundles of

collagen fibers.

This is the strongest kind of cartilage, because it has alternating

layers of hyaline cartilage matrix and thick layers of dense

collagen fibers oriented in the

direction of functional stresses.

This type of cartilage does not have a

perichondrium as it is usually a

transitional layer between hyaline

cartilage and tendon or ligament.

Elastic cartilage:

The picture below is a section of elastic cartilage, stained so

that you can see the elastic fibers. In H&E sections, elastic

cartilage looks the same as hyaline cartilage, so it has to be

specially stained to show the elastic fibers. For example, the Van

Giessen stain stains elastic fibers black.