Question 1

How does the embryo become attached to the uterus?

Accepted Answer

After fertilisation, the zygote undergoes cleavage and develops into a blastocyst. The blastocyst then becomes embedded in the uterine endometrium through implantation.

Question 2

How is the placenta formed?

Accepted Answer

The placenta is a disc-shaped organ attached to the uterine wall. It is formed from the embryo's chorionic villi together with maternal uterine tissues, and the umbilical cord connects it to the embryo.

Question 3

Do maternal and foetal blood normally mix in the placenta?

Accepted Answer

No. Maternal and foetal blood normally remain in separate circulatory pathways. Oxygen, nutrients, carbon dioxide and wastes are exchanged across the chorionic villi rather than by direct mixing.

Question 4

How many umbilical arteries and veins are normally present?

Accepted Answer

The umbilical cord normally contains two umbilical arteries and one umbilical vein. The arteries carry deoxygenated blood from the foetus to the placenta, while the vein carries oxygenated blood back to the foetus.

Question 5

What surrounds the embryo inside the uterus?

Accepted Answer

The embryo is enclosed in the amniotic cavity, which is lined by the amnion and contains amniotic fluid. This fluid-filled cavity surrounds and protects the developing embryo.

Pregnancy and Placenta 3D — Implantation, Cord and Maternal-Foetal Exchange

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