Ovaries, the female gonads, are located below the digestive system in the abdominal cavity.  Inside each ovary are many follicles which consist of a single egg cell and one or more layers of follicle cells.  Follicle cells protect and nourish the egg cells.  A woman is born with about 400,000 follicles and cannot produce more.

     Ovulation is the process in which an egg is expelled from a follicle.  The egg is expelled directly into the abdominal cavity and is picked up by the fallopian tubes.  Inside the fallopian tubes are cilia which sweep the egg into the uterus.  At the neck of the uterus is the cervix which leads into the .  The vagina has very thin walls, much thinner than those of the uterus.

     At the end of the are two pairs of folded skin, the libia minora and the libia majora.  At the top of the libia is glans clitoris, a small bulb of erectile tissue.  Like glans penis, glans clitoris is very sensitive to stimuli.

     Before fertilization can occur, the sperm must reach the egg.  Each egg is only viable for 12 to 48 hours and some sperm can survive for as long as 72 hours, but most can only retain their fertilizing power for 12 to 48 hours.  Therefore in order to produce offspring, sex must occur no more than 72 hours before ovulation or no later than 24 hour after.

     The moment of ejaculation, millions of sperm are propelled into the female’s reproductive tract.  Some sperm immediately leak out of the .  The rest then are able to propel themselves up through the vagina towards the cervix.  As they travel many are killed by the acidity of the vaginal fluids.  The few sperm that are able to make it to the cervix are then exposed to contractions of the uterus that cause a washing machine effect in the uterine cavity.  Here thousands of sperm are hunted down and killed by phagocytes which recognize them as “non-self.”  Of the millions of sperm that are ejaculated, only a few thousand are able to reach the egg.

     When the sperm reaches the egg, it cannot immediately fertilize it.  Instead it must wait in order to allow their membranes to become capacitated, or weakened.  This is facilitated by the cervical mucus, and in the following 6-8 hours the sperm are gradually capacitated.

      After capacitation has occurred, a reaction called the acrosomal reaction can occur.  This reaction releases enzymes in the area surrounding the egg therefore weakening the intracellural cement that surrounds the egg.  Once weakened a single sperm is allowed to penetrate the egg and fertilize it.