Which extraembryonic membrane in humans prevents desiccation of the embryo inside the uterus?

Explanation

Note: Amnion is a type of extraembryonic membrane formed by the amniogenic cells inside and splanchnopleuric extraembryonic mesoderm outside. Amnion surrounds the embryo creating the amniotic cavity that is filled with amniotic fluid. The amniotic fluid serves as a shock absorber for the foetus, regulates foetal body temperature and prevents desiccation. The correct option is: b) Amnion. Explanation of each option: a) Yolk sac: The yolk sac is an extraembryonic membrane present in early embryonic development. In humans, it is involved in providing nutrients to the developing embryo during the early stages of pregnancy. However, it does not play a significant role in preventing desiccation of the embryo inside the uterus. b) Amnion: This is the correct option. The amnion is an essential extraembryonic membrane that surrounds the developing embryo in a fluid-filled sac called the amniotic sac. The amniotic sac is filled with amniotic fluid, which serves multiple important functions. One of its crucial roles is to protect the developing embryo from desiccation (drying out) inside the uterus. The amniotic fluid provides a watery environment that keeps the embryo moist, preventing it from drying out and maintaining a stable and protected environment for the growing fetus. c) Chorion: The chorion is another extraembryonic membrane that forms part of the placenta and plays a significant role in nutrient and gas exchange between the developing embryo and the mother's uterus. While the chorion is vital for the establishment and function of the placenta, it is not directly involved in preventing desiccation of the embryo. d) Allantosis: The allantosis is an extraembryonic membrane that also contributes to the development of the placenta in some species. However, in humans, the allantosis is relatively small and not as prominent as in other animals. It plays a limited role in human embryonic development and is not primarily responsible for preventing desiccation of the embryo. In summary, option (b) Amnion is the correct option. The amnion and the amniotic fluid it contains are crucial in humans for preventing desiccation of the embryo inside the uterus, providing a protective and moist environment for the growing fetus during pregnancy.