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Name: Elaine
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Question:
How are umbilical cords differennt between mammals and birds?


Replies:
Elaine,

Avians (birds), lay eggs, so there is no umbilical cord between the mother and the offspring.

Matt Voss


Bird embryos are placed inside a shell before being laid, and therefore do not have umbilical cords.

J. Elliott


The umbiical cord of mammals provide the nutrient and waste exchange between the growing embryo and the mother. Birds lay eggs which contain a nutrient yolk sac and the allantois that stores wastes and allows for improved gas exchange. There is no umbilical cord. It is interesting to note that in early mammal development, the yolk sac and allantois is present, but do not function as they do with birds. Evolutionary connection here.

S. Sample


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