The part of the egg that is attached to the wall of the uterus grows to form the umbilical cord. At the end of the umbilical cord, a large spongy pad full of blood vessels grows to form the placenta. The embryo gets all its food and oxygen from the mother’s blood. But the mother’s blood and the baby’s blood never mix.
When a baby girl is born, she has about 200 000 eggs. However, the eggs will not develop until certain changes take place in her body. These changes begin at the start of the adolescence stage when changes happen to the inside and outside of her body. The most noticeable changes are the growth of breasts and pubic hair, and the start of menstruation.