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Which extraembryonic membrane in humans prevents desiccation of the embryo inside the uterus?
A
Yolk sac
B
Amnion
C
Chorion
D
Allantois
Detailed Solution
The amnion is the innermost extraembryonic membrane, which surrounds the embryo and encloses the amniotic cavity.
This cavity is filled with amniotic fluid, in which the embryo floats.
The amniotic fluid keeps the embryo moist and so prevents its desiccation; it also acts as a shock absorber and protects the embryo from mechanical injury.
The chorion is the outermost membrane, which takes part in the formation of the placenta.
The allantois contributes to the blood vessels of the umbilical cord, and the yolk sac is the early site of blood cell formation in humans.
So the membrane that prevents desiccation of the embryo is the amnion.
This cavity is filled with amniotic fluid, in which the embryo floats.
The amniotic fluid keeps the embryo moist and so prevents its desiccation; it also acts as a shock absorber and protects the embryo from mechanical injury.
The chorion is the outermost membrane, which takes part in the formation of the placenta.
The allantois contributes to the blood vessels of the umbilical cord, and the yolk sac is the early site of blood cell formation in humans.
So the membrane that prevents desiccation of the embryo is the amnion.