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Connective tissue
 
 
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Connective tissue is a form of fibrous tissue
Biological tissue

Tissue is a cellular organizational level intermediate between cells and a complete organism. Hence, a tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function....
.

It is one of the four types of tissue in traditional classifications (the others being epithelial
Epithelium

In biology and medicine, epithelium is a Biological tissue composed of cell s that line the cavities and surfaces of structures throughout the body....
, muscle
MUSCLE

MUSCLE is public domain, multiple sequence alignment software for protein and nucleotide sequences.MUSCLE is integrated into UGENE bioinformatics tool as a plugin....
, and nervous tissue
Nervous tissue

Nervous tissue is one of four major classes of vertebrate Biological tissue. The function of the nervous tissue is in communication between parts of the body....
).

Collagen
Collagen

Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content....
 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.

s largely a category of exclusion rather than one with a precise definition, but all or most tissues in this category are similarly:

Blood, cartilage
Cartilage

Cartilage is a type of dense connective tissue. It is composed of specialized cells called chondrocyte that produce a large amount of extracellular matrix composed of collagen fibers, abundant ground substance rich in proteoglycan, and elastin fibers....
, and bone
Bone

Bones are rigid organ that form part of the endoskeleton of vertebrates. They function to move, support, and protect the various organs of the body, produce red blood cell and white blood cells and store minerals....
 are usually considered connective tissue, but, because they differ so substantially from the other tissues in this class, the phrase "connective tissue proper" is commonly used to exclude those three.






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Connective tissue is a form of fibrous tissue
Biological tissue

Tissue is a cellular organizational level intermediate between cells and a complete organism. Hence, a tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function....
.

It is one of the four types of tissue in traditional classifications (the others being epithelial
Epithelium

In biology and medicine, epithelium is a Biological tissue composed of cell s that line the cavities and surfaces of structures throughout the body....
, muscle
MUSCLE

MUSCLE is public domain, multiple sequence alignment software for protein and nucleotide sequences.MUSCLE is integrated into UGENE bioinformatics tool as a plugin....
, and nervous tissue
Nervous tissue

Nervous tissue is one of four major classes of vertebrate Biological tissue. The function of the nervous tissue is in communication between parts of the body....
).

Collagen
Collagen

Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content....
 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.

Terminology

It is largely a category of exclusion rather than one with a precise definition, but all or most tissues in this category are similarly:
  • Involved in structure and support.
  • Derived from mesoderm
    Mesoderm

    One of the three germ layers found in the embryos of animals more complex than cnidarians, making them triploblastic. Mesoderm forms in the embryo during gastrulation when some of the cells migrating inward to form the endoderm, produce an additional layer that lies between the endoderm and the ectoderm....
    , usually.
  • Characterized largely by the traits of non-living tissue.


Blood, cartilage
Cartilage

Cartilage is a type of dense connective tissue. It is composed of specialized cells called chondrocyte that produce a large amount of extracellular matrix composed of collagen fibers, abundant ground substance rich in proteoglycan, and elastin fibers....
, and bone
Bone

Bones are rigid organ that form part of the endoskeleton of vertebrates. They function to move, support, and protect the various organs of the body, produce red blood cell and white blood cells and store minerals....
 are usually considered connective tissue, but, because they differ so substantially from the other tissues in this class, the phrase "connective tissue proper" is commonly used to exclude those three. There is also variation in the classification of embryonic connective tissues; on this page they will be treated as a third and separate category.

Classification

Connective tissue can be classified into three categories: proper, embryonic, and specialized.

Connective tissue proper


Connective tissue proper includes the following five types: loose connective, dense connective, elastic, reticular, and adipose. They are called "proper" because they are the types usually meant when using the phrase "connective tissue".

  • Areolar (or loose) connective tissue
    Areolar connective tissue

    Areolar tissue exhibits interlacing, loosely organized fibers, abundant blood vessels, and a lot of seemingly empty space. Its fiber run in random directions and are mostly collagenous, but elastic and reticular fibers are also present....
     holds organs and epithelia in place, and has a variety of protein
    Protein

    Proteins are organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid Residue ....
    aceous fibers, including collagen
    Collagen

    Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content....
     and elastin
    Elastin

    Elastin is a protein in connective tissue that is Elasticity and allows many tissues in the body to resume their shape after stretching or contracting....
    .
  • Dense connective tissue
    Dense connective tissue

    Dense connective tissue, also called dense fibrous tissue, has collagen fibers as its main matrix element. It is mainly composed of collagen type I....
     forms ligament
    Ligament

    Ligaments connect bone to bone. In anatomy, the term ligament is used to denote three different types of structures:# Fibrous Tissue that connects bones to other bones....
    s and tendon
    Tendon

    A tendon is a tough band of fibrous connective tissue that usually connects muscle to bone and is capable of withstanding tension . Tendons are similar to ligaments except that ligaments join one bone to another....
    s. (Some classification systems include fibrous connective tissue
    Fibrous connective tissue

    In zootomy, fibrous connective tissue is a type of connective tissue which has relatively high tensile strength, due to a relatively high concentration of collagen or elastin fibers....
     instead. It is roughly equivalent to dense regular connective tissue
    Dense connective tissue

    Dense connective tissue, also called dense fibrous tissue, has collagen fibers as its main matrix element. It is mainly composed of collagen type I....
    .)
  • Elastic tissue
  • Reticular connective tissue
    Reticular connective tissue

    Reticular connective tissue is a type of connective tissue proper. It has a network of reticular fibers, made of type III collagen. Reticular fibers are not unique to reticular connective tissue, but only in this type are they dominant....
     is a network of reticular fibres (fine collagen, type III) that form a soft skeleton to support the lymphoid organs (lymph nodes, bone marrow
    Bone marrow

    Bone marrow is the flexible biological tissue found in the hollow interior of bones. In adults, marrow in large bones produces new blood cells....
    , and spleen
    Spleen

    The spleen is an organ found in all vertebrate animals. In humans, the spleen is located in the abdomen of the body, where it functions in the destruction of redundant red blood cells, and holds a reservoir of blood....
    .)
  • Adipose tissue
    Adipose tissue

    In histology, adipose tissue or fat is loose connective tissue composed of adipocytes. Adipose tissue is derived from lipoblasts. Its main role is to store energy in the form of fat, although it also cushions and Thermal insulation the body....
     contains adipocyte
    Adipocyte

    Adipocytes are the cell s that primarily compose adipose tissue, specialized in storing energy as fat.There are two types of adipose tissue, white adipose tissue and brown adipose tissue , which are also known as white fat and brown fat, respectively, and comprise two types of fat cells....
    s, used for cushioning
    Cushioning

    Package cushioning is used to help protect fragile items during shipment. It is not uncommon for a transport package to be dropped, kicked, and impacted: These events may produce potentially damaging shocks....
    , thermal insulation
    Thermal insulation

    The term thermal insulation can refer to materials used to reduce the rate of heat transfer, or the methods and processes used to reduce heat transfer....
    , lubrication
    Lubrication

    Lubrication is the process, or technique employed to reduce wear of one or both surfaces in close proximity, and moving relative to each another, by interposing a substance called lubricant between the surfaces to carry or to help carry the load between the opposing surfaces....
     (primarily in the pericardium
    Pericardium

    The pericardium is a double-walled sac that contains the heart and the roots of the great vessels....
    ) and energy
    Energy

    In physics, energy is a scalar physical quantity that describes the amount of Work_ that can be performed by a force. Energy is an attribute of objects and systems that is subject to a conservation law....
     storage.


Embryonic connective tissues

The two types of embryonic connective tissues are mesenchymal and mucous. They are of minimal importance in the adult.
  • Mesenchymal connective tissue
    Mesenchyme

    Mesenchyme is a type of loose connective tissue, of mesodermal origin and located within the embryo mesoderm, consisting of a ground substance Matrix containing a loose aggregate of unspecialized cell which are capable of developing into connective tissue, bone, cartilage, the lymphatic system, and the circulatory system....
  • Mucous connective tissue
    Mucous connective tissue

    Mucous connective tissue is a type of connective tissue found during fetal development.It is most easily found as a component of Wharton's jelly....


Specialized connective tissues

The category "specialized connective tissue" consists of bone, cartilage, and blood. Although these items are connective tissue, they are often considered separately.

  • Blood
    Blood

    Blood is a specialized bodily fluid that delivers necessary substances to the body's Cell s ? such as nutrients and oxygen ? and transports waste products away from those same cells....
     functions in transport. Its extracellular matrix is blood plasma
    Blood plasma

    Blood plasma is the liquid component of blood, in which the blood cells are suspended. It makes up about 55% of total blood volume. It is composed of mostly water , and contains dissolved proteins, glucose, clotting factors, mineral ions, Hormone and carbon dioxide ....
    , which transports dissolved nutrient
    Nutrient

    A nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment....
    s, hormone
    Hormone

    Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism....
    s, and carbon dioxide
    Carbon dioxide

    Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
     in the form of bicarbonate
    Bicarbonate

    In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid. Its chemical formula is HCO3−....
    . The main cellular component is red blood cell
    Red blood cell

    Red blood cells are the most common type of blood cell and the vertebrate body's principal means of delivering oxygen to the body tissues via the blood....
    s.


The following two can be classified as "supportive connective tissue":
  • Bone
    Bone

    Bones are rigid organ that form part of the endoskeleton of vertebrates. They function to move, support, and protect the various organs of the body, produce red blood cell and white blood cells and store minerals....
     (osseous tissue) makes up virtually the entire skeleton in adult vertebrates.
  • Cartilage
    Cartilage

    Cartilage is a type of dense connective tissue. It is composed of specialized cells called chondrocyte that produce a large amount of extracellular matrix composed of collagen fibers, abundant ground substance rich in proteoglycan, and elastin fibers....
     makes up virtually the entire skeleton in chondrichthyes
    Chondrichthyes

    Chondrichthyes or cartilaginous fishes are jawed fish with paired Fins, paired nares, scales, two-chambered hearts, and skeletons made of cartilage rather than bone....
    . In most other vertebrate
    Vertebrate

    Vertebrates are members of the subphylum Vertebrata, chordates with Vertebras or Vertebral columns. The grouping sometimes includes the hagfish, which have no vertebrae, but are genetically quite closely related to lampreys, which do have vertebrae....
    s, it is found primarily in joint
    Joint

    A joint is the location at which two or more bones make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally....
    s, where it provides cushioning. The extracellular matrix of cartilage is composed primarily of collagen
    Collagen

    Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content....
    .


Alternate systems

The old classification system for connective tissue is proper versus specialized. There has been a new classifications system proposed, however, and it is as follows:

Loose connective tissue
  • Areolar
  • Adipose
  • Reticular
Dense connective tissue
Dense connective tissue

Dense connective tissue, also called dense fibrous tissue, has collagen fibers as its main matrix element. It is mainly composed of collagen type I....
  • Regular
  • Irregular
  • Elastic
Cartilage
  • Hyaline
  • Fibrocartilage
  • Elastic
Other
  • Bone
  • Blood
  • Lymphatics


Fiber types

Fiber types as follows:
  • collagenous fibers
  • elastic fibers
    Elastic fibers

    Elastic fibers are bundles of proteins found in extracellular matrix of connective tissue and produced by fibroblasts and smooth muscle cells in artery....
  • reticular fibers


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.It is sometimes inherited as a Autosomal dominant trait. It is carried by a gene called FBN1, which encodes a connective protein called fibrillin-1....
     - a genetic disease causing abnormal fibrillin
    Fibrillin

    Fibrillin is a glycoprotein, which is essential for the formation of elastic fibers found in connective tissue....
    .
  • 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....
     - caused by a dietary deficiency in vitamin C
    Vitamin C

    Vitamin C or ascorbic acid is an essential nutrient for humans, a large number of simian species, a small number of other mammalian species , a few species of birds, and some fish....
    , leading to abnormal collagen
    Collagen

    Collagen is the main protein of connective tissue in animals and 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 rare genetic disorders affecting humans caused by a defect in collagen synthesis. Depending on the individual mutation, the severity of the syndrome can vary from mild to life-threatening....
     - 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 ....
     - a genetic disease related to Marfan syndrome, with an emphasis on vascular deterioration.
  • Pseudoxanthoma elasticum
    Pseudoxanthoma elasticum

    Pseudoxanthoma elasticum 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 is a chronic Autoimmunity connective tissue 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 without the proper protein , or 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 is an extremely rare disease of the connective tissue. A mutation of the body's repair mechanism causes fibrous tissue to be ossification when damaged....
     - disease of the connective tissue, caused by a defective gene which turns connective tissue into bone
    Bone

    Bones are rigid organ that form part of the endoskeleton of vertebrates. They function to move, support, and protect the various organs of the body, produce red blood cell and white blood cells and store minerals....
    .
  • Spontaneous pneumothorax
    Pneumothorax

    In medicine , a pneumothorax, or collapsed lung, is a potential medical emergency caused by accumulation of air or gas in the pleural cavity....
     - collapsed lung, believed to be related to subtle abnormalities in connective tissue.
  • Sarcoma
    Sarcoma

    A sarcoma is a cancer of the connective tissue resulting in mesoderm proliferation.This is in contrast to Carcinoma, which are of Epithelium origin ....
     - 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
    Masson's trichrome

    Masson's trichrome is a three-color staining protocol used in histology. The recipes evolved from the original Masson's formulation to different specific applications, but all are suited for distinguishing cell from surrounding connective tissue....
     stain
  • Mallory's Aniline Blue stain
  • Azocarmine stain
  • Krajian's Aniline Blue stain


External links