Connective tissue

Connective tissue is a fibrous tissue. It is one of the four traditional classes of tissues (the others being epithelial, muscle, and nervous tissue). Connective Tissue (CT) is found throughout the body. It has 3 main components; cells, fibers, and extracellular matrix. Connective tissue makes up a variety of physical structures including, tendons, blood, cartilage, bone, adipose tissue, and lymphatic tissue. CT is classified into three subtypes; Embryonic CT, Proper CT, and Special CT. The Proper CT subtype include dense regular CT, dense irregular CT, and loose CT. The Special CT subtype includes Cartilage, Bone, Adipose Tissue, Blood, Hematopoietic Tissue (tissue that makes blood cells) and Lymphatic Tissue.

Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content.

Functions of connective tissue

 * Storage of energy
 * Protection of organs
 * Providing structural framework for the body
 * Connection of body tissues

Fiber types and characteristics of the connective tissue
Not to be confused with muscle fibers Characteristics of Connective tissue:
 * Cells are spread through an extracellular fluid.
 * Ground Substance - A clear, colorless, and viscous fluid that slows the spread of pathogens.
 * Fibers. Not all types of connective tissues are fibrous though. Examples are adipose tissue and blood. Adipose tissue gives "mechanical cushion" to our body. The matrix of blood is plasma.

Disorders of connective tissue
Various connective tissue conditions have been identified; 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 - deficient type III collagen- 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.
 * Loeys-Dietz syndrome - a genetic disease related to Marfan syndrome, with an emphasis on vascular deterioration.
 * Pseudoxanthoma elasticum - an autosomal recessive hereditary disease, caused by calcification and fragmentation of elastic fibres, affecting the skin, the eyes and the cardiovascular system.
 * Systemic lupus erythematosus - a chronic, multisystem, inflammatory disorder of probable autoimmune etiology, occurring predominantly in young women.
 * Osteogenesis imperfecta (brittle bone disease) - caused by insufficient production of good quality collagen to produce healthy, strong bones.
 * Fibrodysplasia ossificans progressiva - disease of the connective tissue, caused by a defective gene which turns connective tissue into bone.
 * Spontaneous pneumothorax - collapsed lung, believed to be related to subtle abnormalities in connective tissue.
 * Sarcoma - a neoplastic process originating within connective tissue.

Staining of connective tissue
For microscopic viewing the majority of the connective tissue staining techniques color tissue fibers in contrasting shades. Collagen may be differentially stained by any of the following techniques:
 * Van Gieson's stain
 * Masson's Trichrome stain
 * Mallory's Aniline Blue stain
 * Azocarmine stain
 * Krajian's Aniline Blue stain
 * Eosin