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- n. Plural form of evagination.
Sorry, no etymologies found.
There are 2 primary groups of anatomies specializing in gas exchange: 1. organs formed as evaginations (B), e.g., gills; 2. organs formed as invaginations (C), e.g., lungs.
Diverticulum - la: an oft-shoot from a vessel or from the alimentary canal usually blind or sac-like: applied to the caecal tubes or pouches: any extensions or evaginations of the hypodermic.
(Remak's _Hornblatt_), and gives origin to the medullary tube with all its evaginations, and to the skin with all its derivatives and pockets.
These two head-cavities are the only ones to be seen, in this animal, unless the small evaginations from their walls represent other cavities fused with these.
In the outer part of the intermediate cell-mass, immediately under the ectoderm, in the region from the fifth cervical to the third thoracic segments, a series of short evaginations from each segment grows dorsalward and extends caudalward, fusing successively from before backward to form the pronephric duct.
The original evaginations form a series of transverse tubules each of which communicates by means of a funnel-shaped ciliated opening with the celomic cavity, and in the course of each duct a glomerulus also is developed.
Three others appear as disk-like evaginations on the surface of the vesicle; the central parts of the walls of the disks coalesce and disappear, while the peripheral portions persist to form the semicircular ducts; of these the superior is the first and the lateral the last to be completed (Fig. 902).