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Related to chorioallantoic membrane: allantois
extraembryonic membrane formed by fusion of chorion and allantois.
chorioallantoic membrane A highly vascularised extra-embryonic membrane formed in birds and reptiles by apposition of the allantois to the inner face of the chorion.
chorioallantoic membrane Comparative zoology An extraembryonic membrane formed in birds and reptiles by the apposition of the allantois to the inner face of the chorion; the CM is highly vascularized