Elastic cartilage, fibroelastic cartilage or yellow fibrocartilage is a type of

cartilage Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...

present in the

pinnae The auricle or auricula is the visible part of the ear that is outside the head. It is also called the pinna (Latin for "wing" or " fin", plural pinnae), a term that is used more in zoology. Structure The diagram shows the shape and location ...

(auricles) of the ear giving it shape, provides shape for the lateral region of the

external auditory meatus The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the pinna to the eardrum and is about in length and in diameter. Str ...

, medial part of the

auditory canal The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the pinna to the eardrum and is about in length and in diameter. Struc ...

Eustachian tube In anatomy, the Eustachian tube, also known as the auditory tube or pharyngotympanic tube, is a tube that links the nasopharynx to the middle ear, of which it is also a part. In adult humans, the Eustachian tube is approximately long and in d ...

, corniculate and

cuneiform Cuneiform is a logo-syllabic script that was used to write several languages of the Ancient Middle East. The script was in active use from the early Bronze Age until the beginning of the Common Era. It is named for the characteristic wedge-sha ...

laryneal cartilages, and the

epiglottis The epiglottis is a leaf-shaped flap in the throat that prevents food and water from entering the trachea and the lungs. It stays open during breathing, allowing air into the larynx. During swallowing, it closes to prevent aspiration of food int ...

. It contains elastic fiber networks and collagen type II fibers. The principal protein is

elastin Elastin is a protein that in humans is encoded by the ''ELN'' gene. Elastin is a key component of the extracellular matrix in gnathostomes (jawed vertebrates). It is highly elastic and present in connective tissue allowing many tissues in the bod ...

Structure

Elastic cartilage is

histologically Histology, also known as microscopic anatomy or microanatomy, is the branch of biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single ...

similar to

hyaline cartilage Hyaline cartilage is the glass-like (hyaline) and translucent cartilage found on many joint surfaces. It is also most commonly found in the ribs, nose, larynx, and trachea. Hyaline cartilage is pearl-gray in color, with a firm consistency and has ...

but contains many yellow elastic fibers lying in a solid matrix. These fibers form bundles that appear dark under a microscope. The elastic fibers require special staining since when it is stained using haematoxylin and eosin (H&E) stain it appears the same as hyaline cartilage. Verhoeff van Geison stains are used (giving the elastic fibers a black color), but aldehyde fuchsin stains, Weigert's elastic stains, and orcein stains also work. These fibers give elastic cartilage great flexibility so that it is able to withstand repeated bending. Similarly to hyaline one or multiple chondrocytes lie between the spaces (or lacunea) in the fibres. the chondrocytes only make up 2% of the tissue's volume. chondrocytes and the extracellular matrix are contained in an outerlayer named the

perichondrium The perichondrium (from Greek el, περί, peri, around, label=none and el, χόνδρος, chondros, cartilage, label=none) is a layer of dense irregular connective tissue that surrounds the cartilage of developing bone. It consists of two sep ...

(which is a layer of dense irregular connective tissue that surrounds cartilage which is independent of the joint). It is found in the epiglottis (part of the larynx), and the

(the external ear flaps of many mammals). Elastin fibers stain dark purple/black with

Verhoeff's stain Verhoeff's stain, also known as Verhoeff's elastic stain (VEG) or Verhoeff–Van Gieson stain (VVG), is a staining (biology), staining protocol used in histology, developed by United States, American Ophthalmology, ophthalmic surgeon and pathologist ...

. The extracellular matrix contains

Elastin Elastin is a protein that in humans is encoded by the ''ELN'' gene. Elastin is a key component of the extracellular matrix in gnathostomes (jawed vertebrates). It is highly elastic and present in connective tissue allowing many tissues in the bod ...

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, whic ...

glycoproteins Glycoproteins are proteins which contain oligosaccharide chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycos ...

collagen Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole ...

types II, IX, X, and XI, and the

proteoglycan Proteoglycans are proteins that are heavily glycosylated. The basic proteoglycan unit consists of a "core protein" with one or more covalently attached glycosaminoglycan (GAG) chain(s). The point of attachment is a serine (Ser) residue to whic ...

aggrecan. the components within the extracellular matrix are produced by the

chondroblasts Chondroblasts, or perichondrial cells, is the name given to mesenchymal progenitor cells in situ which, from endochondral ossification, will form chondrocytes in the growing cartilage matrix. Another name for them is subchondral cortico-spongious ...

located within the edges of the perichondrium. Elastic fibers within the extracellular matrix are made up of elastin proteins which co-polymerize with fibrillin forming fiber-like elastic chains. When the elastic fibers are relaxed the elastic chains appear disorganized, when

tensile In physics, tension is described as the pulling force transmitted axially by the means of a string, a rope, chain, or similar object, or by each end of a rod, truss member, or similar three-dimensional object; tension might also be described as t ...

pressure is give the elastic chains appear organized and return to a disorganized state when the pressure is released. Collagen fibers form networks to provide strength and structural framework for the molecules within the extracellular matrix.

Function

* Provide support * Maintain shape in response to tension, compression, and bending

References

External links

* - "epiglottis" *
Histology at ucsd.edu
* Skeletal system Connective tissue {{musculoskeletal-stub