Describe the events that lead to pregnancy from the time a zygote is formed, up to the formation of the foetus including the development of the placenta and umbilical cord - NSC Life Sciences - Question 4 - 2021 - Paper 1

As the division continues, the morula develops into a hollow structure called the blastocyst. This occurs as cells continue to proliferate and differentiate.

The blastocyst then travels to the uterus where it implants itself into the endometrial lining. This process is referred to as implantation.

Once implantation occurs, the outer layer of the embryo forms the chorion, while the inner layer develops into the amnion. The amniotic fluid fills this cavity, providing cushioning and a controlled environment.

After implantation, the chorion develops finger-like projections called chorionic villi. These villi, along with the endometrium, form the placenta, which facilitates nutrient and gas exchange between the embryo and maternal blood.

The umbilical cord develops between the foetus and the placenta. It consists of a hollow tube that contains the blood vessels known as the umbilical arteries and vein.

For the first 8 to 12 weeks of development, the mass is referred to as the embryo. As differentiation of tissues occurs and by the end of this period, the developing organism is recognized as a foetus.