Human reproduction: the sequence

1. OVULATION

An ovary releases an egg.

2. FERTILISATION

A sperm nucleus joins with the egg nucleus, usually in an oviduct.

3. EARLY DEVELOPMENT

The fertilised cell divides as it moves towards the uterus.

4. IMPLANTATION

The embryo embeds in the lining of the uterus.

5. DEVELOPMENT

The placenta exchanges nutrients, oxygen and wastes.

Fertilisation and implantation happen in different places.