|THE FEMALE REPRODUCTIVE SYSTEM|
WHAT IS A "TRUE EGG"?
“Eggs” are produced in the ovaries, BUT these are not "true eggs" yet, and will never complete meiosis (a special type of cell division) and become "true eggs" unless OR until they are first fertilized by a sperm. Within the ovary, a follicle consists of one potential egg cell surrounded by special cells to nourish and protect it.
HOW MANY EGGS DOES A WOMAN ACTUALLY HAVE?
A human female typically has about 400,000 follicles/potential eggs, all formed before birth. Only several hundred (about 480) of these “eggs” will actually ever be released during her reproductive years. Normally, in humans, after the onset of puberty, due to the stimulation of follicular-stimulating-hormone (FSH) one “egg” per cycle matures and is released from its ovary. One month the left ovary will release a potential egg and the next month the right ovary will release a potential egg.
WHAT IS OVULATION?
Ovulation is the release of a mature “egg” due to the stimulation of leutenizing hormone (LH), which then stimulates the remaining follicle cells to turn into a corpus luteum (temporary secretory structure which forms from remains of ovarian follicle), which then secretes progesterone to prepare the uterus for possible implantation. If an egg is not fertilized by a sperm and does not implant, the corpus luteum disintegrates and when it stops producing progesterone, the lining of the uterus breaks down and is shed.
WHERE DOES THE FERTILIZED EGG GO?
Each “egg” is released into the abdominal cavity near the opening of one of the oviducts or Fallopian tubes. Cilia (tiny hairs) in the oviduct set up currents that draw the egg in. If sperm are present in the oviduct (if the couple has recently had intercourse), the egg will be fertilized near the far end of the Fallopian tube, will quickly finish meiosis (a special type of cell division), and the embryo will start to divide and grow as it travels to the uterus. The trip down the Fallopian tube takes about a week as the cilia (tiny hairs) in the tube propel the unfertilized “egg” or the embryo down to the uterus. Once the egg is fertilized it is now an "embyro."
At this point, if she had intercourse near the time of ovulation, the woman has no idea whether an unfertilized “egg” or a new baby is travelling down that tube. During this time, progesterone secreted by the corpus luteum (secretory structure) has been stimulating the endometrium (the lining of the uterus) to thicken in preparation for possible implantation, and when a growing embryo finally reaches the uterus, it will implant in this nutritious environment and begin to secrete its own hormones to maintain the endometrium (the lining of the uterus). If the “egg” was not fertilized, it dies and disintegrates, and as the corpus luteum (secretory structure) also disintegrates, its progesterone production falls, and the unneeded, built-up endometrium (the lining of the uterus) is shed.
WHAT IS THE SIZE OF A NORMAL UTERUS?
The uterus has thick, muscular walls and is very small. In a nulliparous woman (a woman who has never been pregnant), the uterus is only about 7 cm long by 4 to 5 cm wide, but it can expand to hold a 4 kg baby. The lining of the uterus is called the endometrium, and has a rich capillary supply to bring food to any embryo that might implant there.
WHAT'S UP WITH CERVICAL MUCUS?
The bottom end of the uterus is called the cervix. The cervix secretes mucus, the consistency of which varies with the stages in a woman's menstrual cycle. At ovulation, this cervical mucus is clear, runny, and conducive to sperm. At post-ovulation, the mucus gets thick and pasty to block sperm. Enough of this mucus is produced that it is possible for a woman to touch a finger to the opening of her vagina and obtain some of it. If she does this on a daily basis, she can use the information, along with daily temperature records, to tell where in her cycle she is.
In the absence of pregnancy, production of estradiol and progesterone begins to decline approximately 7 days after ovulation and this results in shedding of the endometrium (as menstrual bleeding) 11-16 days after ovulation. The Billings Ovulation Method utilizes the changes in cervical mucus production as observed by the woman herself for identifying the underlying events of the ovulatory cycle.
WHAT HAPPENS TO THE CERVIX DURING PREGNANCY?
If a woman becomes pregnant, the cervical mucus forms a plug to seal off the uterus and protect the developing baby, and any medical procedure which involves removal of that plug carries the risk of introducing pathogens into the nearly-sterile uterine environment.
WHAT ABOUT THE VAGINA?
The vagina is a relatively-thin-walled chamber. It serves as a repository for sperm (it is where the penis is inserted), and also serves as the birth canal. Unlike the male, the female has a separate opening for the urinary tract and reproductive system.
These openings are covered externally by two sets of skin folds. The thinner, inner folds are the labia minora and the thicker, outer ones are the labia majora. The labia minora contain erectile tissue like that in the penis, thus change shape when the woman is sexually aroused.
WHAT IS THE HYMEN AND WHERE IS IT?
The opening around the genital area is called the vestibule. There is a membrane called the hymen that partially covers the opening of the vagina. This is torn by the woman’s first sexual intercourse (or sometimes other causes like injury or some kinds of vigorous physical activity).
CLEANING THE VAGINAL AREA
In women, the openings of the vagina and urethra are susceptible to bacterial infections if fecal bacteria are wiped towards them. Sometimes parents who are toilet-training a toddler usually wipe her from back to front, thus “imprinting” that sensation as feeling “right” to her, it is important, rather, that that little girls be taught to wipe themselves from the front to the back to help prevent vaginal and bladder infections. Older girls and women who were taught the wrong way need to make a conscious effort to change their habits.
WHERE IS THE CLITORIS?
At the anterior end (front) of the labia, under the pubic bone, is the clitoris, which is the female equivalent of the penis. This small structure contains erectile tissue and many nerve endings in a sensitive glans within a prepuce (fold of skin), which totally encloses the glans. This is the most sensitive point for female sexual stimulation, so sensitive that "vigorous and direct" stimulation may not feel good. It is better for the man to gently stimulate near the clitoris rather than right on it.
IS THERE SUCH THING AS FEMALE CIRCUMCISION?
Some cultures do a procedure, similar to circumcision, as a puberty rite in teenage girls in which the prepuce is cut, exposing the extremely-sensitive clitoris. There are some interesting speculations on the cultural significance of this because the sensitivity of the exposed clitoris would probably make having sexual intercourse a much less pleasant experience for these women.
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