Connective tissue
Overview
 
"Connective tissue" is a fibrous tissue
Biological tissue
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...

. It is one of the four traditional classes of tissues (the others being epithelial
Epithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...

, muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

, and nervous tissue
Nervous tissue
Nervous tissue is one of four major classes of vertebrate tissue.Nervous tissue is the main component of the nervous system - the brain, spinal cord, and nerves-which regulates and controls body functions...

). Connective Tissue (CT) is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of the body and act as an entity. CT has 3 main components; cells, fibers, and extracellular matrix, all embedded in the body fluids.
Encyclopedia
"Connective tissue" is a fibrous tissue
Biological tissue
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...

. It is one of the four traditional classes of tissues (the others being epithelial
Epithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...

, muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

, and nervous tissue
Nervous tissue
Nervous tissue is one of four major classes of vertebrate tissue.Nervous tissue is the main component of the nervous system - the brain, spinal cord, and nerves-which regulates and controls body functions...

). Connective Tissue (CT) is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of the body and act as an entity. CT has 3 main components; cells, fibers, and extracellular matrix, all embedded in the body fluids. Fibroblasts are the cells responsible for the production of connective tissue. The interaction of the fibers, the extracellular matrix and the water together, form the pliable connective tissue as a whole. Connective tissue makes up a variety of physical structures including, tendons and the connective framework of fibers in muscles, capsules and ligaments around joints, cartilage, bone, adipose tissue, blood 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
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...

, bone
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...

, adipose tissue
Adipose tissue
In histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...

, blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

, hematopoietic tissue (tissue that makes blood cells) and lymphatic tissue
Lymphatic system
The lymphoid system is the part of the immune system comprising a network of conduits called lymphatic vessels that carry a clear fluid called lymph unidirectionally toward the heart. Lymphoid tissue is found in many organs, particularly the lymph nodes, and in the lymphoid follicles associated...

.
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 containing glycosaminoglycans and proteoglycans to fix the bodywater and the collagen fibers in the intercellular spaces. Ground substance slows the spread of pathogens.
  • Fiber
    Fiber
    Fiber is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread.They are very important in the biology of both plants and animals, for holding tissues together....

    s. Not all types of connective tissues are fibrous though. Examples are adipose tissue and blood. Adipose tissue gives "mechanical cushioning" to our body. Although there is no dense collagen network in adipose tissue, groups of adipose cells are kept together by collagen fibers and collagen sheets in order to keep fat tissue under compression in place (for example the sole of the foot). The matrix of blood is plasma.
  • Both the ground substance and proteins(fibers) create the matrix for connective tissue.

Types of connective tissue>
Tissue Purpose Components Location
Collagen
Collagen
Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...

ous fibers
- Alpha polypeptide chains tendon, ligament, skin, cornea, cartilage, bone, blood vessels, gut, and intervertebral disc.
Elastic fibers - elastic microfibrill & elastin extracellular matrix
Reticular fiber
Reticular fiber
Reticular fibers or reticulin is a histological term used to describe a type of fiber in connective tissue composed of type III collagen. Reticular fibers crosslink to form a fine meshwork...

s
- - liver, bone marrow, lymphatic organs

Disorders of connective tissue

Various connective tissue conditions have been identified; these can be both inherited and environmental.
  • Marfan syndrome
    Marfan syndrome
    Marfan syndrome is a genetic disorder of the connective tissue. People with Marfan's tend to be unusually tall, with long limbs and long, thin fingers....

     - a genetic disease causing abnormal fibrillin
    Fibrillin
    Fibrillin is a glycoprotein, which is essential for the formation of elastic fibers found in connective tissue.Fibrillin is secreted into the extracellular matrix by fibroblasts and becomes incorporated into the insoluble microfibrils, which appear to provide a scaffoldfor deposition of elastin.It...

    .
  • Scurvy
    Scurvy
    Scurvy is a disease resulting from a deficiency of vitamin C, which is required for the synthesis of collagen in humans. The chemical name for vitamin C, ascorbic acid, is derived from the Latin name of scurvy, scorbutus, which also provides the adjective scorbutic...

     - caused by a dietary deficiency in vitamin C
    Vitamin C
    Vitamin C or L-ascorbic acid or L-ascorbate is an essential nutrient for humans and certain other animal species. In living organisms ascorbate acts as an antioxidant by protecting the body against oxidative stress...

    , leading to abnormal collagen
    Collagen
    Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...

    .
  • Ehlers-Danlos syndrome
    Ehlers-Danlos syndrome
    Ehlers–Danlos syndrome is a group of inherited connective tissue disorders, caused by a defect in the synthesis of collagen . The collagen in connective tissue helps tissues to resist deformation...

     - 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
    Loeys-Dietz syndrome
    Loeys-Dietz syndrome is a recently-discovered autosomal dominant genetic syndrome which has many features similar to Marfan syndrome, but which is caused by mutations in the genes encoding transforming growth factor beta receptor 1 or 2 .It was identified and characterized by American physician...

     - a genetic disease related to Marfan syndrome, with an emphasis on vascular deterioration.
  • Pseudoxanthoma elasticum
    Pseudoxanthoma elasticum
    Pseudoxanthoma elasticum , also known as Grönblad–Strandberg syndrome, is a genetic disease that causes fragmentation and mineralization of elastic fibers in some tissues. The most common problems arise in the skin and eyes, and later in blood vessels in the form of premature atherosclerosis...

     - 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
    Systemic lupus erythematosus
    Systemic lupus erythematosus , often abbreviated to SLE or lupus, is a systemic autoimmune disease that can affect any part of the body. As occurs in other autoimmune diseases, the immune system attacks the body's cells and tissue, resulting in inflammation and tissue damage...

     - a chronic, multisystem, inflammatory disorder of probable autoimmune etiology, occurring predominantly in young women.
  • Osteogenesis imperfecta
    Osteogenesis imperfecta
    Osteogenesis imperfecta is a genetic bone disorder. People with OI are born with defective connective tissue, or without the ability to make it, usually because of a deficiency of Type-I collagen...

     (brittle bone disease) - caused by insufficient production of good quality collagen to produce healthy, strong bones.
  • Fibrodysplasia ossificans progressiva
    Fibrodysplasia ossificans progressiva
    Fibrodysplasia ossificans progressiva , sometimes referred to as Stone Man Syndrome, is an extremely rare disease of the connective tissue. A mutation of the body's repair mechanism causes fibrous tissue to be ossified when damaged. In many cases, injuries can cause joints to become permanently...

     - disease of the connective tissue, caused by a defective gene which turns connective tissue into bone
    Bone
    Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...

    .
  • Spontaneous pneumothorax
    Pneumothorax
    Pneumothorax is a collection of air or gas in the pleural cavity of the chest between the lung and the chest wall. It may occur spontaneously in people without chronic lung conditions as well as in those with lung disease , and many pneumothoraces occur after physical trauma to the chest, blast...

     - collapsed lung, believed to be related to subtle abnormalities in connective tissue.
  • Sarcoma
    Sarcoma
    A sarcoma is a cancer that arises from transformed cells in one of a number of tissues that develop from embryonic mesoderm. Thus, sarcomas include tumors of bone, cartilage, fat, muscle, vascular, and hematopoietic tissues...

     - a neoplastic process originating within connective tissue.
  • Hemangiopericytoma
    Hemangiopericytoma
    A hemangeopericytoma is a type of soft tissue sarcoma that originates in the pericytes in the walls of capillaries. When inside the nervous system, although not strictly a meningioma tumor, it is a meningeal tumor with an especially aggressive behavior.It was characterized in...

     - a neoplastic process

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
    Masson's trichrome
    Masson's trichrome is a three-colour staining protocol used in histology. The recipes evolved from Claude L. Pierre Masson's original formulation to different specific applications, but all are suited for distinguishing cells from surrounding connective tissue....

     stain
  • Mallory's Aniline Blue stain
  • Azocarmine stain
  • Krajian's Aniline Blue stain
  • Eosin
    Eosin
    Eosin is a fluorescent red dye resulting from the action of bromine on fluorescein. It can be used to stain cytoplasm, collagen and muscle fibers for examination under the microscope. Structures that stain readily with eosin are termed eosinophilic....


External links

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