Histology Fact Sheet: Cartilage

Histology of Cartilage

Of the four basic tissue types (epithelium, connective tissue, muscle and nervous tissue), connective tissue is the most diverse. Cartilage is a type of connective tissue.

When looking at the histology it can be seen that cartilage consists of cells and fibers within a matrix (or ground substance).

The mature cell in cartilage is a chondrocyte.

A lacuna is a small space or depression. The space that the chondrocyte rests in is a lacuna. The lacuna is surrounded by matrix.

The matrix of cartilage is 60-80% water. The matrix (ground substance) of cartilage is composed of proteoglycans and glycosaminoglycans. Proteoglycans are composed of a protein core and attached glycosaminoglycans. Chondroitin sulfate, keratan sulfate, and hyaluronic acid are all glycosaminoglycans.

A chondroblast is an immature cartilage cell which produces the cartilaginous matrix.

Cartilage is avascular. Nutrients reach cartilage by diffusion from the adjacent tissues.

The perichondrium is the connective tissue which surrounds cartilage. Histology hint from Sarah Bellham: The prefix "peri" means around, such as in the word "perimeter".

Cartilage arises from mesenchyme.

There are three types of cartilage: hyaline cartilage, elastic cartilage and fibrocartilage. All three types of cartilage are composed of chondrocytes residing in lacunae and a hydrous extracellular matrix. All three types of cartilage are avascular.

Top of Page

Histology of Hyaline Cartilage

Histology slide of hyaline cartilage. Histology slide courtesy of an anonymous donation.

Hyaline cartilage is the most abundant type of cartilage.

Hyaline cartilage forms the skeleton of the fetus. The cartilage forms a template of the bones. Endochondral ossification will occur during the childhood, replacing the hyaline cartilage with bone. Hyaline cartilage forms the epiphyseal growth plate.

Hyaline cartilage forms the articular surface on bones.  The rings of the trachea are composed of hyaline cartilage. Costal cartilage is the cartilage at the end of the ribs. It is hyaline cartilage. The larynx is composed of several cartilages. The thyroid cartilage, cricoid cartilage, arytenoid cartilages, corniculate cartilages and cuneiform cartilages are all composed of hyaline cartilage. (The epiglottis is elastic cartilage. There is no fibrocartilage in the larynx.) The "Adam's apple" is a nickname for part of the larynx formed by the thyroid cartilage.

Hyaline cartilage is characterized by a glassy matrix. Histology hint from Sarah Bellham: The word hyaline is derived from the Greek word "hyalos" which means glass. It is also used the word hyalophagia (glass eating).

Top of Page

Histology of Elastic Cartilage

Elastic cartilage has elastic fibers in the matrix.

Elastic cartilage is sometimes referred to as yellow cartilage.

Elastic cartilage is found in the external ear. Histology hint from Sarah Bellham: If you bend your ear forward, it bounces back into its proper position. This is due to the elastic cartilage.

Elastic cartilage is found in the walls of the eustachian tube. The epiglottis is part of the larynx. It is composed of elastic cartilage.

Top of Page

Histology of Fibrocartilage

Fibrocartilage has thick bundles of collagen fibers in the matrix. Fibrocartilage is sometimes referred to as white cartilage.

Fibrocartilage forms the symphysis pubis. Fibrocartilage forms the intervertebral disc. Fibrocartilage is present in the temporomandibular joint.

Top of Page

Sources:

Human Anatomy
Elaine N Marieb; Jon Mallatt

Histology: A Text and Atlas
Michael H. Ross/Edward J. Reith