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 ...
present in the
pinnae (auricles) of the ear giving it shape,
provides shape for the lateral region of the
external auditory meatus,
medial part of the
auditory canal 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- ...
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 in ...
. 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 bo ...
.
Structure
Elastic cartilage is
histologically 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 h ...
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 s ...
(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
pinnae (the external ear flaps of many mammals). Elastin fibers stain dark purple/black with
Verhoeff's stain.
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 bo ...
,
fibrillin,
glycoproteins,
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 whol ...
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
Aggrecan (ACAN), also known as cartilage-specific proteoglycan core protein (CSPCP) or chondroitin sulfate proteoglycan 1, is a protein that in humans is encoded by the ''ACAN'' gene. This gene is a member of the lectican (chondroitin sulfate pr ...
.
the components within the extracellular matrix are produced by the
chondroblasts 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 a ...
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
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