Question

Which is the structure that connects the fetus to the placenta?

• A. Amnion
• B. Umbilical cord
• C. Chorion
• D. Yolk sac

Answer 1

The correct option is B

Umbilical cord

The correct option is C.

The explanation for the correct answer:

1. In placental mammals, the umbilical cord correlates the maturing embryo or foetus to the placenta.
2. The umbilical cord has two umbilical arteries and one umbilical vein.
3. The umbilical cord helps in the movement of blood, nutrients and oxygen from the mother to the foetus.

The explanation for the incorrect options:

Option A:

1. The amnion fills with amniotic fluid, which causes the amnion to grow and produce the amniotic sac, which protects the developing foetus.
2. The amnion protects the embryo, together with the chorion, yolk sac, and allantois.

Option B:

1. In mammals, birds, and reptiles, the chorion is the outermost foetal membrane that surrounds the embryo.
2. It begins as an outside fold on the yolk sac's surface that is outside the zona pellucida.

Option D:

1. In a growing embryo, the yolk sac is the first structure discovered and enclosed within the gestational sac.
2. A gestational sac is a fluid-filled pouch that forms inside the uterus and encases the embryo and yolk sac.

Final answer: The umbilical cord is the structure that connects the foetus to the placenta.