Human Biology, 14 Edition

Published by McGraw-Hill Education
ISBN 10: 1-25924-574-8
ISBN 13: 978-1-25924-574-9

Chapter 18 - Section 18.1 - Fertilization - Check Your Progress - Page 388: 2


18.2:2 Extra-embryonic membranes include amnion, allantois, chorion, and yolk sac. 1. Amnion: The amnion contains fluid that bathes the embryo, cushions and protects it. 2. Allantois: This membrane gives rise to the urinary bladder; itc ollects embryogenic urine (the nitrogenous waste) produced by the kidneys . 3. The yolk sac: Many blood vessels develop from the yolk sac; it is the first site of blood cell formation.

Work Step by Step

4. The chorion forms the fetal half of the placenta; chorionic villi increase the absorptive area of this membrane, and chorionic blood vessels connect with umbilical blood vessels
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