Implantation & Development of the Foetus
- After fertilisation in the oviduct, the zygote travels towards the uterus
- This usually takes about 3 days, during which time the zygote will divide several times to form a ball of cells known as an embryo
- Once it reaches the uterus, the embryo embeds itself in the thick lining of the uterus (a process known as implantation) and continues to grow and develop
- A placenta forms where the embryo is attached
- The placenta is an organ that ensures materials can be exchanged between the blood of the mother and the blood of the growing embryo
- The umbilical cord joins the embryo's blood supply to the placenta for exchange of nutrients and removal of waste products
- The embryo is surrounded by amniotic fluid (a fluid made from the mother’s blood plasma) that is held in by the amniotic membrane (also known as the amniotic sac)
- The amniotic fluid protects the embryo during development by cushioning it from bumps to the mother’s abdomen
The foetus in the uterus
- For the next 9 months, the embryo grows in the uterus
- This is known as the gestation period
- Major development of organs takes place within the first 12 weeks, during which time the embryo gets nutrients from the mother by diffusion through the uterus lining
- After this point, the organs are all in place, the placenta has fully formed and the embryo is now called a foetus (sometimes spelt fetus)
- The remaining gestation time is used by the foetus to grow bigger in size
