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allantoisenUK
al·lan·to·is A0206200 (ə-lăn′tō-ĭs)n. pl. al·lan·to·i·des (ăl′ən-tō′ĭ-dēz′) A membranous sac that develops from the posterior part of the digestive tract in the embryos of mammals, birds, and reptiles. It is important in the formation of the umbilical cord and placenta in mammals. Also called allantoid.
[New Latin allāntois, variant of allāntoīdēs, from Greek allāntoeidēs, sausage-shaped : allās, allānt-, sausage (perhaps from Greek dialectal (Magna Graecia) *allāwent-, (sausage) seasoned with garlic, from *allā-, garlic, of Italic origin; akin to Latin ālium, garlic; see allium) + -oeidēs, -oid.]
al′lan·to′ic (ăl′ən-tō′ĭk) adj.allantois (ˌælənˈtəʊɪs; əˈlæntɔɪs) n (Zoology) a membranous sac growing out of the ventral surface of the hind gut of embryonic reptiles, birds, and mammals. It combines with the chorion to form the mammalian placenta[C17: New Latin, irregularly from Greek allantoeidēs sausage-shaped, allantoid] allantoic adjal•lan•to•is (əˈlæn toʊ ɪs, -tɔɪs)
n., pl. al•lan•to•i•des (ˌæl ənˈtoʊ ɪˌdiz) a nourishing membrane surrounding the embryo, between the amnion and chorion, in birds and reptiles developing as a sac from the hindgut and in mammals as an inner layer of the placenta. [1640–50; < New Latin < Greek allantoeidḗs (see allantoid).] al`lan•to′ic, adj. al·lan·to·is (ə-lăn′tō-ĭs) A membranous sac that grows out of the lower end of the alimentary canal in embryos of reptiles, birds, and mammals. In mammals, the blood vessels of the allantois develop into the blood vessels of the umbilical cord.Thesaurus| Noun | 1. |  allantois - the vascular fetal membrane that lies below the chorion and develops from the hindgut in many embryonic higher vertebrates (reptiles, birds and mammals)mammal, mammalian - any warm-blooded vertebrate having the skin more or less covered with hair; young are born alive except for the small subclass of monotremes and nourished with milkfetal membrane - any membrane that functions for the protection or nourishment or respiration or excretion of a developing fetus |
allantoisenUK
allantois [ah-lan´to-is] a small sausage-shaped outpouching from the caudal wall of the yolk sac of the early embryo, associated with early blood formation and development of the urinary bladder; its blood vessels become the umbilical arteries and veins. adj., adj allanto´ic.al·lan·to·is (ă-lan'tō-is), A fetal membrane developing from the hindgut (or yolk sac, in humans). In humans it becomes a fibrous cord, the urachus; externally, in other mammals, it contributes to the formation of the umbilical cord and placenta; in birds and reptiles, it lies close beneath the porous shell and serves as an organ of respiration. Synonym(s): allantoid membrane [allanto- + G. eidos, appearance] allantois (ə-lăn′tō-ĭs)n. pl. allantoides (ăl′ən-tō′ĭ-dēz′) A membranous sac that develops from the posterior part of the digestive tract in the embryos of mammals, birds, and reptiles. It is important in the formation of the umbilical cord and placenta in mammals. Also called allantoid.
al′lan·to′ic (ăl′ən-tō′ĭk) adj.allantois An extraembryonic membranous sac found in a developing animal conceptus, which is comprised of all embryonic and extraembryonic tissues. It is intimately involved in gas and liquid waste exchange, as well as erythropoiesis; it gives rise to the foetal umbilical arteries and vein and contributes to the formation of the urinary bladder.al·lan·to·is (ă-lan'tō-is) A fetal membrane developing from the hindgut (or umbilical vesicle, in humans). In humans it becomes a fibrous cord, the urachus; externally, in mammals, it contributes to the formation of the umbilical cord and placenta.
Synonym(s): allantoid membrane. [allanto- + G. eidos, appearance]allantois A membranous sac that develops from the hindgut in the EMBRYO and takes part in the formation of the umbilical cord and the PLACENTA.allantois a membranous growth from the central side of the hind gut of the developing vertebrate embryo that extends outside the embryo proper and is covered by a layer of connective tissue containing many blood vessels. In birds and reptiles the allantois acts as a respiratory surface with the allantoic cavity (see Fig. 30 being used for the storage of excretory materials. In placental mammals the allantoic blood vessels carry blood to and from the PLACENTA for respiration, nutrition and excretion. In all groups most of the allantois is detached at birth.allantoisenUK
Related to allantois: yolk sac, urachus, Vitelline ductWords related to allantoisnoun the vascular fetal membrane that lies below the chorion and develops from the hindgut in many embryonic higher vertebrates (reptiles, birds and mammals)Related Words- mammal
- mammalian
- fetal membrane
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