List of abbreviations		 Vocabulary
of micros-
copic
anatomy
specialist terms
explained in
English +
German

Every attempt was made to provide correct information and labelling, however any liability for eventual errors or incompleteness is rejected!
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Editor:
Dr. med.
H. Jastrow
Conditions
of use
Overview elastic fibres (Fibrae elasticae):
Pages with explanations are linked to the text below the images if available! (Labelling is in German)
elastic and collagen fibres
(monkey)		 elastic & collagen
fibres (human)		 elastic and collagen
fibres (rat)		 elastic fibres of the membrana elastica interna
of an arteriole in ovary stroma (rat)		 elastic membrane of an
arteriole(rat)
Aorta: Tunica media with
elastic fibre network (monkey)		 membrana elastica interna
of an arteriole (rat)		 elastic membrane
human umbilical artery		 detail thereof
(human)		 large elastic fibre bordered by
collagen fibres of human subcutis
Elastic fibres (Terminologia anatomica: Fibrae elasticae) are extracellular connective tissue fibres that can reversibly be stretched up to twice their original length. They consist of a central amorphous hardly electron-dense substance called elastin (Terminologia histologica: Elastinum) that often appears blurred in sections. It is surrounded and partly infiltrated by tiny very electron-dense fibrillin fibrils (Terminologia histologica: Fibrillae fibrillini). These extracellular microfilaments have diameters of  6 to 8 nm and serve for anchoring the elastic fibres to surrounding tissues. Fibrillin alone (without elastin) is encountered in the zonular fibres between the ciliar body and the capsule of the eye lens. Such fibrillin bundles totally lacking elastin are called oxytalan fibres (Terminologia histologica: Fibrae oxytalanae) and are very rare. Another kind of rare fibres called elaunin fibres (Terminologia histologica: Fibrae elauninae) consist of fibrillin bundles with sparsely aggregated elastin. The amorphous elastin biochemically is similar to collagen and is rich in glycine and proline. It further contains some hydroyxproline but lacks hydroxylysine which in collagen is responsible for the aggregation in form of tropocollagen. Apart from valin only desmosin and isodesmosin are interlinking the polypeptid chains in elastin. In contrast to collagen fibrils polypeptid chains are singly cross-linked in elastin and arrange increasingly parallel when stretched. When stretching is over they draw back the macromolecules into the original aggangement which is the basis for the elastic character of elastic fibres. The stronger the lengthening effect of an elastic fibre is the more power is necessary for further stretching.
Elastin is synthetised and released into the extracellular matrix in form of proelastin by fibroblasts and smooth muscle cells. It then is cross-linked by enzymes of the extracellular space. Elastic fibres are very stable and long-lasting. They even are insoluble in boiling water. Further they are quite resitant to acids ond bases. Degenerative changes such as deposition of calcium salts will result in reduced elasticity in older age.
Elastic fibres appear shiny in light microscopy by their strong light-diffraction and require special stains such as resorcin-fuchsin to become homogenously blackly stained. Non-stretched fibres appear isotrop in polarised light. With increase of lengthening peptid molecule arragement gets more and more parallel resulting in a stetch-anisotropy. The thickness of the fibres ranges from some hundret nanometers up to 4 µm. Elastic fibres often form meshworks and they condense as elastic membranes in the walls of arteriols and arteries: Membrana elastica interna and -externa. Elastic fibres are present in loose and fibrous connective tissue, in the stroma of organs (e.g. in the lung) and in capsules of organs. Connective tissue appears slightly yellow when it has a high content of elastic fibres e.g., Ligamenta flava, aorta, elastic cartilage). A high content of elastic fibres is also seen in the vocal cords and the wall of the gut.

--> reticular fibres, collagen fibres, fibroblasts, connective tissue, ground substance
--> Electron microscopic atlas Overview
--> Homepage of the workshop

Two images were kindly provided by Prof. H. Wartenberg; other images, page & copyright H. Jastrow.