Name the four extra embryonic membranes.

Question 34 of 43

Q. Name the four extra embryonic membranes.

Telangana TsbieTelangana Board of Intermediate Education (Intermediate 1st Year) 2020Subjective· 2mImportance★★★★★

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Concept understanding — Extra-embryonic Membranes

Extra-embryonic Membranes

A developing embryo is fragile and has needs — it must not dry out, it needs food, it needs oxygen, and it needs to get rid of wastes. In animals that develop on land or inside the mother, the embryo solves these problems by building a set of protective, life-support membranes around itself. These are the extra-embryonic membranes, and they were a key innovation that allowed vertebrates to conquer dry land.

Why "extra-embryonic"?

They are called extra-embryonic because, although they form from the embryo's own tissues, they lie outside the embryo's body and do not become part of the adult animal. They are temporary support structures — a kind of built-in life-support system — discarded at or after birth/hatching.

The four membranes and their jobs

Amniotes — the reptiles, birds and mammals — develop four such membranes:

Membrane	Function
Amnion	Encloses the embryo in a fluid-filled sac; the amniotic fluid cushions it against shock and prevents drying out
Chorion	The outermost membrane; involved in protection and in gas exchange (in mammals it contributes to the placenta)
Allantois	Stores nitrogenous waste and assists in respiration/gas exchange; in mammals contributes to the umbilical connection
Yolk sac	Encloses the yolk and supplies stored food (nutrition) to the developing embryo

The big picture — why they matter …

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Amniotes (reptiles, birds, mammals) develop four extra-embryonic membranes — amnion, chorion, yolk sac, and allantois — that protect and support the embryo.

In amniote vertebrates, the developing embryo is enclosed and supported by four accessory (extra-embryonic) membranes, which arise from the embryonic germ layers but lie outside the embryo's own body:

Amnion — the innermost membrane; encloses the embryo in a fluid-filled amniotic cavity that cushions it against shock and prevents desiccation.
Chorion — the outermost membrane, lying just inside the eggshell (or forming part of the placenta in mammals); involved in gas exchange.
Yolk sac — encloses the yolk and, in yolk-rich eggs, digests and transports nutrients to the growing embryo; also an early site of blood cell formation. …

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Q.Name the four extra embryonic membranes.

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