Sexual intercourse and fertilisation

During sexual intercourse sperm are transferred from the penis of the male into the vagina of the female. They then swim through the uterus to the oviduct and can fertilise an egg cell if one is present.

Step one: Once every 28 days an egg cell is released from the ovary and moves into the oviduct (ovulation).

The human female reproductive system working during reproduction and fertilisation. The egg is released from the ovary and moves toward the oviduct.

Step two: During sexual intercourse sperm is ejaculated into the vagina. Sperm moves through the vagina, cervix, uterus and along the oviduct.

The egg cell is released from the ovary into the oviduct.  A sperm has been ejaculated into the vagina and is travelling up the cervix.

Step three: It is in the oviduct that fertilisation takes place. The nucleus of one sperm fuses with the nucleus of an egg forming a zygote that contains genetic material from both parents. This random combination of parental gametes leads to variation within the species.

The egg and sperm meet at the oviduct and the process of fertilisation begins.