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Pronunciation: ko're-o-a-lan'to-is

Definition: Extraembryonic membrane formed by the fusion of the allantois with the serosa or false chorion. In mammalian embryos, it forms the fetal portion of the placenta; in avian embryos, it is fused with the shell.

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© Copyright 2018 Wolters Kluwer. All Rights Reserved. Review date: Sep 19, 2016.