Ovulation is the time when an egg or ova is released by a women's Ovary. The egg travels through Fallopian tubes and if a sperm from the male is also present in the tube, fertilization of the egg occurs and a a woman conceives. Once released, the egg can survive for up to 24 hours The hormone responsible for release of the egg is called 'Luteinising Hormone' and is produced by the brain. The sudden surge in the level of the hormone releases the egg and also causes a small increase in the Body Temperature.