Facts About Reproduction Female Reproductive System
At the middle of the menstrual cycle, an ovary releases (ovulates) a mature egg, which the fallopian tube picks up—one end of the tube is right next to the ovary. The tube moves the egg back towards the uterus.
If sexual intercourse occurs around this time, the sperm swim through the lower opening to the uterus (cervix). They travel though the uterine cavity to the tubal openings and into each tube. Fertilization occurs in the outer third of the tube containing the egg.
Fertilized or not, the egg reaches the uterus about 4–5 days after ovulation. If healthy, a fertilized egg now contains 100–200 cells (and is now called a blastocyst). It imbeds into the uterine lining (endometrium).
If fertilization does not occur or the embryo is not viable, the uterine lining sheds about one week later (the menstrual period).
Hormones and ovulation
Hormones from the pituitary gland at the base of the brain control ovulation. Follicle-stimulating hormone (FSH) prompts an egg to grow and mature. Ovulation does not occur in alternating ovaries in alternating months. Usually, just one egg matures at a time, randomly in either ovary.
A cycle is from the start of one menstrual period to the next. When the egg is mature at the middle of the cycle, the pituitary gland releases luteinizing hormone (LH), called the "LH surge." This prompts the egg to enter into final maturation and to be released. The actual release of the egg is what we refer to as ovulation.
Contraception
If a woman does not wish to conceive and is sexually active, she should use a form of contraception.
Barrier methods include diaphragms and condoms, which are usually more effective when used with contraceptive foam.
Hormonal methods include birth control pills, Depo-Provera shots, contraceptive implants, and vaginal rings. The active ingredient in all of these methods is the hormone progesterone. It inhibits development of the uterine lining. It also keeps cervical mucus in a state that is not likely to allow sperm to pass from the vagina into the uterus and up into the tubes.
Intrauterine devices (IUDs) disrupt the development of the uterine lining, preventing implantation. They may also contain progesterone.
