Fertilisation and Implantation 1

Once they are released, sperm swim through the uterus and oviduct.

Sperm stop for refreshments at cells present in the uterus lining and oviduct.

The egg is released from the ovary.
It is surrounded by a small ball of cells derived from the follicle - the Corona radiata.

After its release the egg is only viable for 24 hours.

Successful fertilisation can only occur within this period, which means that the egg (secondary oocyte) is normally fertilised in the top half of the oviduct.