Structures and Characteristics
Feathers are among the most complex integumentary appendages found in vertebrates and are formed in tiny follicles in the epidermis, or outer skin layer, that produce keratin proteins. The β-keratins in feathers, beaks and claws — and the claws, scales and shells of reptiles — are composed of protein strands hydrogen-bonded into β-pleated sheets, which are then further twisted and crosslinked by disulfide bridges into structures even tougher than the α-keratins of mammalian hair, horns and hoof. The exact signals that induce the growth of feathers on the skin are not known but it has been found that the transcription factor cDermo-1 induces the growth of feathers on skin and scales on the leg.
Read more about this topic: Feather
Other articles related to "structure, structures, structures and characteristics":
... An orphan structure is a financing term referring to a company whose shares are held by a trustee on a non-charitable purpose trust ... Orphan structures are usually used in offshore structures to ensure that the assets and liabilities of the subject company are treated as "off-balance-sheet ... Other reasons for creating an orphan structure are to avoid or minimise regulation which might otherwise apply to a structure, and to ensure that the company is "bankruptcy remote" from companies in the ...
... is usually clearer images, especially of structures that are difficult to view transthoracicly (through the chest wall) ... All these structures, along with the increased distance the beam must travel, weaken the ultrasound signal thus degrading the image and Doppler quality ... In adults, several structures can be evaluated and imaged better with the TEE, including the aorta, pulmonary artery, valves of the heart, both atria, atrial septum ...
... alignment with the sides of the 4.6-metre (15 ft) wide playing area formed by Structures Sub-2 and Sub-4 ... The southern limit of the ballcourt is formed by Structure Sub-1, just over 11 metres (36 ft) to the south of Structures Sub-2 and Sub-4, creating a southern end-zone that runs east–west and ... Structure 5 is a large pyramid on the west side of Terrace 3 ...
... The Schoolhouse at Truxton Canyon Training School in Valentine operated from 1903-1937 as a mandatory boarding school in which Hualapai were separated from their families and put to work learning various trades ... Long a symbol of forced assimilation, the historic building is now the property of the Hualapai Nation ...
... of feathers are produced by pigments, by microscopic structures that can refract, reflect, or scatter selected wavelengths of light, or by a combination of both ... of light reflecting from different layers of the structures in feathers, in the case of green plumage in addition to the yellow pigments the specific feather structure involved is sometimes called the Dyck ...
Famous quotes containing the word structures:
“It is clear that all verbal structures with meaning are verbal imitations of that elusive psychological and physiological process known as thought, a process stumbling through emotional entanglements, sudden irrational convictions, involuntary gleams of insight, rationalized prejudices, and blocks of panic and inertia, finally to reach a completely incommunicable intuition.”
—Northrop Frye (b. 1912)