from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The act of evaginating
from the GNU version of the Collaborative International Dictionary of English
- n. The act of unsheathing.
- n. An outgrowth or protruded part.
from The Century Dictionary and Cyclopedia
- n. The act of unsheathing. Craig.
- n. In zoology: The act or process of evaginating, unsheathing, or withdrawing; hence, a protrusion of some part or organ.
- n. That which is protruded, unsheathed, or evaginated: said of any protrusible part or organ.
Sorry, no etymologies found.
The primary requirement for a body appendage or evagination to be identified as a gill or ctenidium is the high vascularization of the respiratory surface.
The parietal and visceral mesoblast, or the two middle layers, are always of later origin, and arise through evagination or plaiting of the entoblast, the remainder of which can now be distinguished as secondary entoblast from the primary.
They distinguished in the middle layer two quite distinct elements, the mesoblast proper, formed by the evagination of the walls of the archenteron, and the mesenchyme, formed by free cells budded off from the germ-layers.
Rapid growth concentrated at one point brings about an evagination; in this manner are formed the sense-organs from the nerve-tube, the liver and lungs from the alimentary tube.
The evagination to form the hypophysis, _p_, is seen against the floor of the forebrain, _fb_.
In lizards the pineal evagination is elongated into a stalk, and its peripheral extremity is expanded into a vesicle, in which a rudimentary lens and retina are formed; the stalk becomes solid and nerve fibers make their appearance in it, so that in these animals the pineal body forms a rudimentary eye.
The pineal body arises as an upward the evagination of roof-plate immediately in front of the midbrian; this evagination becomes solid with the exception of its proximal part, which persists as the recessus pinealis.
The posterior commissure is formed by the ingrowth of fibers into the depression behind and below the pineal evagination, and the trigonum habenulæ is developed in front of the pineal recess.
Philipp I, Aufschnaiter R, Ozbek S, Pontasch S, Jenewein M, et al. (2009) Wnt/beta-catenin and noncanonical Wnt signaling interact in tissue evagination in the simple eumetazoan Hydra.