Reproductive System Of A Woman
The sexual and reproductive organs on the outside of a woman’s body are called the external genitals. There are three openings in the genital area. In front is the urethra, from where urine comes out; below the urethra is the opening to the vagina which is called the introitus, and the third is the anus from where a bowel movement leaves the body.
The outer genital area is called the vulva. The vulva includes the clitoris, the labia majora and the labia minora. The most sensitive part of the genital area is the clitoris. This is a pea-shaped organ which is full of nerve endings and its only purpose is to provide sexual pleasure. The clitoris is protected by a hood of skin, and is the equivalent of the male’s penis.
The labia majora, or outer lips, surround the opening to the vagina. They are made of fatty tissue that cushions and protects the vaginal opening. Between these outer lips are labia minora, or inner lips. These lips are sensitive to sexual stimuli. As they get stimulated, they take on a deeper color and begin to swell.
The vagina is a muscular tunnel that connects the uterus (or womb) to the outside of the body. The vagina provides an exit for the menstrual fluid, and an entrance for the male’s semen which is ejaculated during sexual intercourse. Normally flat, like a collapsed balloon, the vagina is extremely flexible and can stretch to accommodate a tampon, a penis or even a baby’s head (during childbirth) ! The walls of the vagina are muscular, smooth and soft. The vagina is a closed space which ends at the cervix.
The uterus, or the womb, is the place where the fertilized egg grows and develops into a baby during pregnancy. The uterus lies
deep in the lower abdomen—the pelvis—and is just behind the urinary bladder. The uterus is a hollow organ shaped like a pear and is about the size of the fist. Inside the muscular walls of the uterus is a very rich lining, namely the endometrium, and it is in this lining that the fertilized egg gets implanted. If, however, pregnancy does not occur, this lining is shed along with blood in the form of the menstrual flow.
The neck of the uterus is called the cervix. It connects the uterus to the vagina and contains special glands called crypts that produce mucus which helps to keep bacteria out of the uterus. The cervical mucus also helps sperm in entering the uterus when the egg is ripe.
Two tubes, known as fallopian tubes, are attached to the upper part of the uterus on either side and are about 10 cm long. They are about as thick as a piece of spaghetti. Each tube forms a narrow passageway that opens like a funnel into the abdominal cavity, near the ovaries. The ends of the fallopian tubes are draped over the two ovaries and they serve as a passage for the egg to travel from the ovary into the uterus. Each fallopian tube is lined by millions of tiny hairs called cilia, that beat rhythmically to propel the egg forward. Of course, the tube is not just a pathway—it performs other functions too, including nourishing the egg and the early embryo in its cavity. Also, the sperm fertilize the egg in one of the fallopian tubes.
The two almond-sized ovaries are perched in the pelvis, one on each side, just within the fallopian tubes’ grasp. The ovaries perform two functions: they produce the eggs and they also secrete hormones. Each month, at the time of ovulation, a mature egg is released by an ovary. This egg is “picked up” by the fimbria (a bordering fringe at the end of the fallopian tubes) and drawn into the fallopian tube.
How does the egg reach the fallopian tube?
When ovulation occurs, the mature egg is released from the follicle in the ovary. This process of follicular rupture looks a bit like a small volcano erupting on the ovarian surface. At this time, the tubal fimbria, like tentacles, sweep over the surface of the ovary, and actually “swallow” the egg. The egg has a shell, called the zona pellucida, which looks somewhat like the ring around Saturn. This shell is surrounded by a cluster of nest cells called the corona cells, which serve to nurture the egg. These cells form the cumulus oophorus which is a sticky gel that protects the egg and also helps the beating of the hair-like cilia of the fallopian tube to propel the egg towards the uterus—like a conveyor belt. The egg must now wait in the protective confines of the fallopian tube, for a sperm to swim up and reach it.
The ovary contains about 2 million eggs during the six months of fetal life. From that point onwards, the number of eggs progressively decreases, till only about 300,000 egg cells are left at the time of birth— a lifetime’s stock. During the fertile years, fewer than 500 of these eggs will be released into the fallopian tubes—once in each menstrual cycle. One of the existing eggs becomes matured for ovulation each month, and this limited supply runs out at the time of menopause. Unlike the testes in the male, which are continually churning out billions of new sperms, the ovary never produces any new eggs.