menstruation & fertilisation.
- Wednesday, July 23, 2008 / 12:28 AM.
menstruation. 
when menstruation occurs, the unwanted egg dissolves, and the lining on the uterus wall is shed.
fertilisation. however, if sexual intercourse were to take place within 48 hours of the release of the
egg, the
egg might be fertilised. only ONE
sperm will succeed in entering the
egg, while a barrier will be formed to block out other
sperms. the head will break off from the
sperm, and its nucleus will fuse with the
egg's nucleus.
both the sperm and egg have 23 chromosones, which contain genes that decide on how you look like, your height, and other features of your body.