Connective tissue is any type of biological tissue with an extensive extracellular matrix. There are several basic types:

• Bone contains specialized cells called osteocytes embedded in a mineralized extracellular matrix, and functions for general support.
• Loose connective tissue holds organs and epithelia in place, and has a variety of proteinaceous fibers, including collagen and elastin.
• Fibrous connective tissue forms ligaments and tendons.
• In the osteichthyes, cartilage makes up virtually the entire skeleton. In most other vertebrates, it is found primarily in joints, where it provides cushioning. The extracellular matrix of cartilage is composed primarily of chondroitin sulfate.
• The extracellular matrix of blood is the blood plasma, which transports dissolved nutrients, hormones, and carbon dioxide in the form of bicarbonate. The main cellular component is red blood cells.
• Adipose tissue contains adipocytes, used for cushioning, insulation, and energy storage.

Disorders of connective tissue

Various connective tissue conditions have been described, these can be both inherited and environmental.

• Marfan syndrome - a genetic disease causing abnormal fibrillin.
• Scurvy - caused by a dietary deficiency in vitamin C, leading to abnormal collagen.
• Ehlers-Danlos Syndrome - a genetic disease causing progressive deterioration of collagens, with different EDS types affecting different sites in the body, such as joints, heart valves, organ walls, arterial walls, etc.

See also: zootomy