Allantois Definition

ə-lăntō-ĭs
allantoides
noun
A membranous pouch with a rich blood supply in the embryos of birds, reptiles, and mammals: it is an organ of respiration and excretion for embryonic birds and reptiles: in mammals it helps form the placenta.
Webster's New World
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.
American Heritage Medicine

(anatomy) A sac, having a number of functions, that develops in the alimentary canal of the embryos of mammals, birds and reptiles.

Wiktionary

Other Word Forms of Allantois

Noun

Singular:
allantois
Plural:
allantoides, allantoises

Origin of Allantois

  • New Latin allāntois from allāntoīdes from Greek allāntoeidēs sausage-shaped allās allānt- sausage -oeidēs -oid

    From American Heritage Dictionary of the English Language, 5th Edition

Allantois Sentence Examples

  • It is urged that the imperfect placenta of the bandicoots instead of being vestigial, may be an instance of parallelism, and that in marsupials generally the allantois failed to form a placental connexion.

  • They are separated from fishes and batrachians (Pisces and Batrachians) on the one hand, and agree with reptiles, and birds (Reptilia and A y es) on the other, in the possession during intra-uterine life of the membranous vascular structures respectively known as the amnion and the allantois, and likewise in the absence at this or any other period of external gills.

  • Expansion of the extra-embryonic coelom cavity allows the yolk sac and allantois to expand into the coelom cavity allows the yolk sac and allantois to expand into the coelom cavity from the gut of the embryo.

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Words Starting With

AALALL

Words Ending With

SISOIS

Unscrambles

allantois

Words Starting With A and Ending With S

Starts With A & Ends With SStarts With AL & Ends With SStarts With A & Ends With IS

Word Length

9 Letter Words9 Letter Words Starting With A9 Letter Words Ending With S