Allantois



a vascular, extraembryonic membrane of birds, reptiles, and certain mammals that develops as a sac or diverticulum from the ventral wall of the hindgut.
Historical Examples

An embryonic appendage, the allantois, used in reptiles and birds for respiration, has here been turned to another purpose.
The Whence and the Whither of Man John Mason Tyler

The function of the allantois is still in a great measure unknown.
A System of Midwifery Edward Rigby

The arteries of the allantois are originally the terminations of the primitive aort.
The Anatomy of the Human Peritoneum and Abdominal Cavity George. S. Huntington

The cavity of the allantois, if developed, vanishes completely.
The Works of Francis Maitland Balfour, Volume III (of 4) Francis Maitland Balfour

The allantois becomes a part of the fetal umbilical cord after the formation of the placenta.
The Ethics of Medical Homicide and Mutilation Austin O’Malley

Similar movements are also seen in the allantois at a considerably later period.
The Works of Francis Maitland Balfour, Volume III (of 4) Francis Maitland Balfour

The other part of the archenteron wall make the allantois, the hind gut and the bladder.
The Ethics of Medical Homicide and Mutilation Austin O’Malley

It thus comes about that the further splitting of the mesoblast merely enlarges the cavity in which the allantois lies.
The Works of Francis Maitland Balfour, Volume III (of 4) Francis Maitland Balfour

The fasciculus attached to the embryo is the allantois which becomes the umbilical cord.
The Sexual Question August Forel

As the allantois increases in size and importance, the allantoic vessels are correspondingly developed.
The Works of Francis Maitland Balfour, Volume III (of 4) Francis Maitland Balfour

noun
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

allantois al·lan·to·is (ə-lān’tō-ĭs)
n. pl. al·lan·to·i·des (āl’ən-tō’ĭ-dēz’)
A membranous sac that develops from the posterior part of the alimentary canal in the embryos of mammals, birds, and reptiles, and is important in the formation of the umbilical cord and placenta in mammals. Also called allantoid.
al’lan·to’ic (āl’ən-tō’ĭk) adj.
allantois
(ə-lān’tō-ĭs)
Plural allantoides (āl’ən-tō’ĭ-dēz’)
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.

Tagged:

Read Also:

  • Allantoidoangiopagous twins

    allantoidoangiopagous twins allantoidoangiopagous twins al·lan·toi·do·an·gi·op·a·gous twins (āl’ən-toi’dō-ān’jē-ŏp’ə-gəs) pl.n. Unequal monozygotic twins with fusion of their allantoic vessels within the placenta. Also called omphaloangiopagous twins.

  • Allantoin

    a white powder, C 4 H 6 N 4 O 3 , produced by oxidation of uric acid and the major excretory product of purine degradation in many vertebrates: used medicinally to heal skin ulcers and in lotions, lipsticks, etc., for its soothing effect. noun a substance derived from the secretions of snails and contained […]



  • Allantoinuria

    allantoinuria allantoinuria al·lan·to·i·nu·ri·a (ə-lān’tō-ə-nur’ē-ə, -nyur’-) n. The excretion of allantoin in the urine.

  • Allargando

    becoming slower and broader. adjective, adverb (music) (to be performed) with increasing slowness



Disclaimer: Allantois definition / meaning should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional. All content on this website is for informational purposes only.