Background

To understand how assisted reproductive technology works, it will help to review the basics of the reproductive system.

During each menstrual cycle, an egg or oocyte (ovum) is released by one of the ovaries. This is called ovulation. The egg travels into the fallopian tube. If fertilization is to occur, sperm ejaculated into the vagina must swim up through the cervix and uterus and into the fallopian tube, where a single sperm penetrates the egg. The fertilized egg travels into the uterus and embeds itself in the wall of the uterus (endometrium). This process is called implantation.