Which of the four extra-embryonic membranes maintains the same form and functions in birds and mammals? 08:42 Animal Reproduction and Development Which of the four extra-embryonic membranes maintains the same form and functions in birds and mammals? A - The amnion B - The allantois C - The yolk sac D - The chorion E - None of them Answer: A - The amnion Learn More : Share this Share on FacebookTweet on TwitterPlus on Google+