In the intervertebral regions the membrana elastica externa has become aborted at the posterior border of each vertebra, and the remaining part is considerably puckered transversely.
Around the cuticular sheath of the notochord an elastic membrane, the membrana elastica externa, is next developed.
The sheath of the notochord within the membranaelastica externa is formed of a concentrically striated layer, continuous with the innermost layer of the sheath in the vertebral regions.
In the intervertebral regions the membrana elastica externa is still present in most parts, but has become absorbed at the posterior border of each vertebra, as shewn in longitudinal section in Plate 42, fig.
The neural and haemal arches, resting on the membrana elastica externa, do not at this early stage in the least constrict the notochord.
During the same period, however, the true sheath of the notochord greatly increases in thickness, and the membrana elastica externa becomes more definite.
Around the cuticular sheath of the notochord there is formed an elastic membrane--the membrana elastica externa.
The whole sheath is still invested by a very distinct membrana elastica externa (m.
The inner unmodified layer of the sheath has the appearance in transverse sections through the vertebral regions of an inner membrane, and may perhaps be Koelliker's "membrana elastica interna.
Thus, curiously enough, the membrana elasticaexterna and the sheath of the notochord in the intervertebral regions are folded in different directions, the folds of the one being only visible in transverse sections (Plate 42, fig.
Around the sheath of the notochord there is formed in the Cyclostomata, Ganoidei, Elasmobranchii and Teleostei an elastic membrane usually known as the membrana elastica externa.
The sheath becomes very much thickened; and on the membrana elastica covering it the vertebral arches directly rest.
It is bounded internally by a membrane--the true membrana elastica externa.
The cells which form this layer appear to be derived from a special investment of the notochord, and to have penetrated through the membrana elastica externa to reach their final situation.
Externally is placed the membrana elastica externa (mel), while within is the cuticular sheath of the notochord.
In Teleostei there is present, as in Elasmobranchii, an elastica externa, and an inner notochordal sheath.
Between the membrana elastica externa and the sheath of the notochord a layer of cells becomes interposed (fig.
In the Amphibia and in the Amniota no membrane is present which can be identified with the membrana elastica externa of the Elasmobranchii, Teleostei, etc.
The elastica becomes progressively reduced until it entirely disappears from the middle coat, which then becomes a purely muscular tunic, and, before the capillary is reached, is reduced to a single layer of muscle cells.
Moreover, injections of sodium urate and ergot caused necroses in the muscularis and elastica of the aorta, pulmonary artery, vena cavas inferior and heart muscle, but there was no calcification.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "elastica" in a variety of sentences. We hope that you will now be able to make sentences using this word.
