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Cartilage histology


Cartilage is an avascular, smooth, and elastic tissue with various forms that allow it to function in a variety of ways.

It can act as a smooth surface for bone articulation within joints, play a role in bone formation, and also provide structural support, such as the cartilage rings in the trachea.

The majority of the tissue consists of extracellular matrix or ECM, and only a relatively small number of chondrocyte cells.

Mature chondrocytes are responsible for secreting and maintaining the extracellular matrix of the cartilage.

Based on the appearance and specific function, cartilage is separated into three main types: hyaline cartilage, elastic cartilage, and fibrocartilage.

Hyaline cartilage has a “glassy” appearance and can be found on many articular surfaces as well as cartilage that provides structural support.

Elastic cartilage contains a dense network of branching elastic fibers that allow it to be more flexible, which is why it’s often found in structures that need to be firm, yet still flexible.

Some examples include the epiglottislarynx, and the pinna of the external ear.

And finally, fibrocartilage contains dense connective tissue with collagen fibers, as well as bands of extracellular matrix.

This type of cartilage is found in structures such as the meniscus and intervertebral discs.

Let’s first focus on hyaline cartilage, which is the most common type of cartilage.

This image is an example of hyaline cartilage on the articulating surface of a long bone, with the articulating surface located at the top of the image.

The image on the right is a longitudinal section of the trachea, which is an example of hyaline cartilage providing structural support.

Both images were stained with hematoxylin and eosin or H&E for short. With this stain, the cartilage stains a dark purple due to its strong affinity for hematoxylin.

If we take a closer look at the tracheal hyaline cartilage, it has an outer layer of dense irregular connective tissue surrounding the cartilage called the perichondrium.

The perichondrium is also further separated into an outer fibrous layer and an inner chondrogenic layer.

Within the chondrogenic layer, there are spindle-shaped cells that differentiate into small cells called chondroblasts as they migrate deeper into the cartilage matrix.

These cells will start producing cartilage matrix and eventually mature into chondrocytes.

The chondrocytes are found within small cavities called lacunae that are often arranged in clusters of 2 to 4 cells.

The extracellular matrix, with its “glassy” appearance, is composed of mostly type II collagen and proteoglycan, which is an amorphous gelatinous substance, which is often referred to as ground substance.

Although articular hyaline cartilage is very similar to tracheal hyaline cartilage, a key difference between them is that articular cartilage does not have a perichondrium of connective tissue surrounding it.

The lack of a perichondrium ends up limiting the articular cartilage’s ability to grow.


Cartilage is a unique connective tissue in that it is smooth, elastic, and lacks blood vessels. Its primary function is to provide cushioning and support for the body's joints and other structures, such as the C-shaped rings supporting the trachea. The matrix of cartilage is composed of collagen fibers and proteoglycans, which are highly charged proteins that bind to water. This combination of collagen and proteoglycans gives cartilage its characteristic spongy texture.

Note that there are three types of cartilage. There is hyaline cartilage characterized by an extracellular matrix with a "glassy" appearance. hyaline cartilage is found in the trachea and the articulating surfaces of the long bones. Second is the elastic cartilage, characterized by a dense network of elastic fibers. Elastic cartilage is commonly found in the epiglottis and the pina of the external ear.

Finally, there is fibrocartilage which is a combination of hyaline cartilage and dense connective tissue. This one is found in the knee meniscus and the intervertebral discs. Over time, cartilage can break down due to wear and tear injury or disease. When this happens, the affected joint may become painful and stiff, and in severe cases, the joint may no longer be able to move properly.

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