The female sexual-reproductive system is housed in the pelvis; the major internal organs lie behind and are protected by the pubic bone (pubis symphysis). These organs are situated in close conjunction with the urinary and intestinal tracts, as are the external openings of these three systems.

The ovary, or female gonad, is similar in size and shape to an unshelled almond. The human female has two ovaries, one at the left and one at the right in the pelvic cavity. The ovaries perform two main functions: they produce eggs, or and they manufacture the female hormones, estrogen and progesterone. When a female child is born, her ovaries contain 200,000 to 400,000 follicles holding oocytes, or immature eggs; this number reduces to 100,000 to 200,000 by puberty. The newborn’s ovaries contain all the egg cells she will ever produce. In contrast, once boys reach puberty, their bodies continuously manufacture new sperm. Given that a woman is fertile for approximately 35 years, releasing one egg with each menstrual period 13 times a year, she needs only 450 ova to achieve her maximum reproductive capacity; nature thus provides an overabundance of gamete cells in order to ensure the continuation of the species.

When an individual egg is released at ovulation, it pops out through the surface of the ovary and remains momentarily suspended in the abdominal cavity. It is then, generally, “transferred” to the fingerlike ends of one of the two Fallopian tubes. These tubes are muscular canals, each suspended by a ligament, which extend outward from the uterus a distance of four to six inches. Each Fallopian tube curves around an ovary but is not directly attached to the ovary.

The mechanism by which the egg enters the tube is not fully understood; three theories have been advanced by way of explanation. First, there is the possibility of a chemical affinity, or chemotaxis, between the egg and the entrance of the tube. Secondly, the fringed end of the tube is motile and may engulf the egg in a tentaclelike fashion. Thirdly, the cilia, or tiny hairs, that line the Fallopian tube beat rhythmically in unison, to sweep the egg inward (Cohn, 1974). Once the egg is in the Fallopian tube, it is moved along by the cilia lining the tube and by peristalsis, rhythmic contractions of the tube, in the direction of the uterus. Cases have been reported in the medical literature in which women with only one ovary and one Fallopian tube on the opposite side have nonetheless managed to conceive (Hellman and Pritchard, 1971). In such cases, the expelled egg has migrated from one side of the body cavity to the other, a distance of over six inches.

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