allantois
Noun: 1. A fetal membrane in amniotes: The allantois is an extra-embryonic membrane that develops from the hindgut of the embryos of reptiles, birds, and mammals. It is involved in respiration and excretion, and in mammals, it contributes to the formation of the umbilical cord and placenta.
The term "allantois" is a specialized biological and medical term. It is used almost exclusively in scientific contexts to describe a specific structure in embryonic development. * It functions as a noun. * It typically appears in technical descriptions of embryology, comparative anatomy, and developmental biology.
- In avian embryos, the allantois serves as a respiratory organ and a repository for waste.
- The allantois fuses with the chorion to form the chorioallantoic membrane, which is crucial for gas exchange.
- During mammalian development, the blood vessels of the allantois become the umbilical arteries and vein.
- Chorioallantoic membrane: A structure formed by the fusion of the chorion and the allantois, which is used in research (e.g., the CAM assay) to study angiogenesis or viral growth.
- Allantoic fluid: The liquid contained within the allantoic cavity.
- Allantoic (adjective): Pertaining to the allantois.
- Example: The allantoic cavity stores metabolic waste in bird eggs.
- There are no direct common-language synonyms. In technical contexts, it may be referred to descriptively as a fetal/embryonic membrane or a respiratory/excretory sac.
The word "allantois" has only one specific, technical meaning in modern English related to embryology. It does not have general or figurative meanings.
This is a highly specialized term from embryology. It is not used in everyday conversation and is primarily encountered in academic, veterinary, or medical texts.
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the vascular fetal membrane that lies below the chorion and develops from the hindgut in many embryonic higher vertebrates (reptiles, birds and mammals)
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