| Allantois | |
|---|---|
 Diagram illustrating a chicken egg in its 9th day with all extraembryonic membranes | |
 Allantois and other fetal membranes shown at end of second month of human pregnancy | |
| Details | |
| Pronunciation | /əˈlæntɔɪs/, /əˈlæntoʊɪs/ |
| Days | 16 |
| Identifiers | |
| Latin | allantois |
| MeSH | D000482 |
| TE | E6.0.1.2.0.0.2 |
| Anatomical terminology | |
The allantois (/əˈlæntoʊɪs/ a-LAN-toe-iss;[1] pl.: allantoides or allantoises) is a hollow sac-like structure filled with clear fluid that forms part of a developing amniote's conceptus (which consists of all embryonic and extraembryonic tissues). It helps the embryo exchange gases and handle liquid waste.
The allantois, along with the amnion, chorion, and yolk sac (other extraembryonic membranes), identify humans and other mammals, birds, and reptiles as amniotes. These extraembryonic membranes that form the embryo have aided amniotes in the transition from aquatic to terrestrial environments.[2] Fish and amphibians are anamniotes, lacking the allantois. In mammals the extraembryonic membranes are known as the fetal membranes.
- ^ Jones, Daniel (October 6, 2011). Cambridge English Pronouncing Dictionary. Cambridge University Press. ISBN 9780521765756 – via Google Books.
- ^ Chuva de Sousa Lopes, Susana M.; Roelen, Bernard A. J.; Lawson, Kirstie A.; Zwijsen, An (2022-12-05). "The development of the amnion in mice and other amniotes". Philosophical Transactions of the Royal Society B: Biological Sciences. 377 (1865): 20210258. doi:10.1098/rstb.2021.0258. ISSN 0962-8436. PMC 9574641. PMID 36252226.