Allantois (also known as Allantoic Membrane, Membrane, Allantoic): An extra-embryonic membranous sac derived from the YOLK SAC of REPTILES; BIRDS; and MAMMALS. It lies between two other extra-embryonic membranes, the AMNION and the CHORION. The allantois serves to store urinary wastes and mediate exchange of gas and nu

NIH MeSH · D000482Anatomy

Allantois

Also known asAllantoic Membrane · Membrane, Allantoic

Definition

An extra-embryonic membranous sac derived from the YOLK SAC of REPTILES; BIRDS; and MAMMALS. It lies between two other extra-embryonic membranes, the AMNION and the CHORION. The allantois serves to store urinary wastes and mediate exchange of gas and nutrients for the developing embryo.

MeSH classification

  • A10.615.284.147
  • A16.254.750.147

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Related concepts

Amnion

The innermost membranous sac that surrounds and protects the developing embryo which is bathed in the AMNIOTIC FLUID. Amnion cells are secre…

Common questions about Allantois

What does Allantois mean in medicine?
An extra-embryonic membranous sac derived from the YOLK SAC of REPTILES; BIRDS; and MAMMALS. It lies between two other extra-embryonic membranes, the AMNION and the CHORION. The allantois serves to store urinary wastes and mediate exchange of gas and nutrients for the developing embryo. This definition is taken from the National Library of Medicine's MeSH (Medical Subject Headings) 2026 release, which is the standard vocabulary used to index PubMed and most medical literature.
Is Allantois known by any other names?
Yes. Allantois is also referred to as Allantoic Membrane, Membrane, Allantoic in different clinical, research and patient-facing contexts. The MeSH descriptor groups all of these synonyms under a single canonical concept so research and records stay consistent.
Where does Allantois sit in the medical classification?
Allantois falls under the broader medical category "Anatomy" in the MeSH hierarchy (tree numbers: A10.615.284.147, A16.254.750.147). Browsing the related concepts on this page takes you to neighbouring topics in the same branch of medicine.
Where can I get a plain-language explanation of Allantois?
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Source: NIH MeSH 2026 (D000482) — National Library of Medicine, public domain. View official MeSH record ↗