Meaning of allantois

al•lan•to•is

Pronunciation: (u-lan'tō-is, -tois), [key]

— n. Embryol., Zool.

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

See also:

Infoplease Tools

Video Library

A large collection of informational and educational videos from animals and landmarks to language arts and history.
Almanacs

A vast compendium of statistics and up-to-date facts and figures, on everything you need to know.
Dictionary

An unabridged dictionary from aalii to zymurgy, including a pronunciation guide.
Atlas

An atlas featuring maps and detailed profiles of all 193 countries and the 50 U.S. states.
Encyclopedia

A current and comprehensive encyclopedia covering all the major branches of knowledge from astrophysics to Zimbabwe.