Allantois

: It is derived from the splanchnopleure, which consists of endoderm and splanchnic mesoderm. 2. Functional Diversity Across Species

myesr.org/poster/esr/ecr2020/C-10164/background">urachal cysts or other developmental remnants? allantois

The is a critical extra-embryonic membrane found in the embryos of reptiles, birds, and mammals that primarily functions in waste storage and gas exchange . In egg-laying species, it acts as a repository for nitrogenous waste and works with the chorion to facilitate respiration, while in most mammals, it evolves to form the structure of the umbilical cord. 1. Evolutionary Significance and Structure : It is derived from the splanchnopleure, which

: The allantois is typically small and unattached in most marsupials, though it does fuse with the chorion in specific groups like bandicoots and koalas. while in most mammals