Unit 8: The reproductive system                                                1   2   3

3.4. Gestation

After fertilisation, the zygote start to divide several times until it becomes in a hollow ball of cells, the embryo.

It is dragged towards the uterus by the cilia of the cells of the Fallopian tubes during approximately 7 days. When it reaches the uterus, it sticks to the endometrium. This process is called implantation.

Once implantation occurs the female reproductive system pauses. There is no menstruation or follicle development until the pregnancy ends.

Gestation is the period of time between implantation and birth. During this process the development of the embryo occurs.

After implantation, several organs that will enable the gestation develop:

- Placenta. This organ is formed from the uterus mucosa and from embryo’s tissues. It performs the exchange of substances between the mother and the embryo.

- Umbilical cord. This is the connexion between the placenta and the developing embryo.

- Amniotic sac. This is a bag which embryo develops into, submerged in amniotic fluid.

3.7. Answer the following questions:

a. Why are follicle development and menstruation paused during pregnancy?

b. How does embryo arrive to the uterus after fertilisation? How long does it take?

c. Is a woman pregnant before embryo implantation takes place? Why?

3.8. Listen and identify the described organ:

3.9. Answer these questions:

a.  What is the belly button (navel)?

b.  When can we know the sex of the baby?

c.   In which moment can the mother feel the kicks of the foetus?

d.  Why is very unusual the survival if the baby is born before the six month

   of gestation?