Cartilage and bone, both specialized types of connective tissue, are closely related in structure and function. In fact, most of the bone in the body develops from a type of cartilage during the process of endochondral ossification, as seen in the image at the right. Like other types of connective tissue, cartilage and bone are composed of cells, fibers, and ground substance, but the relative rigidity of their extracellular matrices makes them unique.

Despite the similarities between cartilage and bone, the properties of the cartilage matrix, including its hardness, density, and avascularity, are distinct from those of bone. Bone also has a more extensive set of cell types, possesses extracellular specializations for calcification, and is well vascularized. These characteristics underlie the greater capacity of bone for growth, remodeling, and repair. Cartilage and bone are closely associated in joints, where they work together to allow movement and/or cushioning of adjacent bones.

The learning objectives for this unit are:

1. Identify the three types of cartilage (hyaline, fibrous, and elastic) and their histological features.
2. Identify the cells and structural features within bone.
3. Identify the structural features associated with endochondral bone development.
4. Identify the layers and components of synovial joints and intervertebral discs.  

Let's take a look at some tissues.