Share this entry

Share this page

allantois

Syllabification: al·lan·to·is
Pronunciation: /əˈlan(t)əwəs
 
/

Definition of allantois in English:

noun (plural allantoides /ˌalənˈtō-idēz/)

The fetal membrane lying below the chorion in many vertebrates, formed as an outgrowth of the embryo’s gut. In birds and reptiles it grows to surround the embryo; in eutherian mammals it forms part of the placenta.
Example sentences
  • The urachus is a remnant of allantoic origin, connecting the embryonal cloaca to the allantois during early intrauterine life.
  • In the fetus, the urachus connects the bladder with the allantois.
  • Initially, the bladder is continuous with the allantois.

Origin

mid 17th century: modern Latin, based on Greek allantoeidēs 'sausage-shaped'.

Derivatives

allantoic

1
Pronunciation: /ˌalənˈtō-ik/
adjective
Example sentences
  • We're talking about things like the amnion, the chorion, the allantoic sac, the placenta, the umbilical cord, if those words sound familiar to you.
  • Veterinarians are completing the study comparing allantoic and amniotic fluids and heart rates of fetuses in mares.
  • The embryo forms an allantoic placenta, as is true of at least some peramelids and koalas but not other marsupials.

allantoid

2
adjective
Example sentences
  • The spores are white, and are cylindrical to allantoid in shape.
  • HvAV - 3a virions vary from allantoid to bacilliform, and are not occluded in occlusion bodies.
  • When screening germ plasm for Karnal bunt resistance, allantoid secondary sporidia produced in solid media should be used as inoculum.

Definition of allantois in:

Share this entry

Share this page

 

What do you find interesting about this word or phrase?

Comments that don't adhere to our Community Guidelines may be moderated or removed.

Get more from Oxford Dictionaries

Subscribe to remove adverts and access premium resources

Word of the day terpsichorean
Pronunciation: ˌtəːpsɪkəˈriːən
adjective
relating to dancing