allantois


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Related to allantois: yolk sac, urachus, Vitelline duct

al·lan·to·is

 (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 adj

al•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.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.allantois - the vascular fetal membrane that lies below the chorion and develops from the hindgut in many embryonic higher vertebrates (reptiles, birds and mammals)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 milk
fetal membrane - any membrane that functions for the protection or nourishment or respiration or excretion of a developing fetus
References in periodicals archive ?
The urachus, a midline tubular structure, represents an embryologic remnant of the allantois, the cephalic extension of cloaca that connects the anterior dome of the bladder and the umbilicus.
The CAM consists of two extra-embryonic membranes: the chorion and the allantois, which fuse together on embryonic day (ED) 4.
Table 1: Day of first detection of ultrasonographically First day detected Characteristic Mean Range (days) (days) Embryo proper 20.3 19 to 24 Heartbeat 20.9 19 to 24 Allantois 23.2 22 to 25 Spinal cord 29.1 26 to 33 Forelimb buds 29.1 28 to 31 Amnion 29.5 28 to 33 Eye orbit 30.2 29 to 33 Hindlimb buds 31.2 30 to 33 Placentomes 35.2 33 to 38 Split hooves 44.6 42 to 49 Foetal movement 44.8 42 to 50 Ribs 52.8 51 to 55
Also called the median umbilical ligament, the urachus is a vestigial remnant of two embryonic structures: the cloaca and the allantois [1].
The urachus is a remnant of the fetal structure connecting the allantois and the fetal bladder.
Theurachusisanembryologicalremnantthatoriginatesfrom the involution of the allantois and cloaca, extending from the umbilicus to the bladder dome.
Urachus is a fibrous remnant of the urogenital sinus and allantois. Generally, the urachus involutes after the third trimester and forms the medium umbilical ligament.
Osmoregulation by avian embryos: The allantois functions like a toad's bladder.
The urachus is a tubular structure that connects the bladder to the allantois in the embryonic development, involuting after the third trimester, into a fibromuscular tract or closed canal between the dome of urinary bladder and the umbilicus.