During sexual intercourse, semen is released from the penis into the vagina. This is called ejaculation., Sperm cells swim from the vagina, through the cervix, and into the uterus. Then they travel to the oviduct. Many sperm die before they reach the oviduct., If a sperm cell meets an egg in the oviduct, fertilisation can happen., The fertilised egg divides several times to form a ball of cells called an embryo., The embryo travels down the oviduct and implants in the lining of uterus and begins to develop into a baby. This is called implantation..

KS3 Fertilisation and implantation

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