But Nature has not ventured to subordinate the control of the sexual functions of the woman to her will, and so once every lunar month she involuntarily passes through a series of remarkable transformations which are the expressions of desire on the part of Nature that she shall perpetuate the species. The female sexual apparatus consists primarily of the organs of generation, and secondarily of the organs of lactation the mammary glands or breasts.
The vagina is the sexual passage which extends upward from the external genitals to the womb; it serves as the organ of copulation and is the chief part of the "birth passage" during the delivery of the foetus.
The uterus, or womb, is a pear shaped, hollow, muscular organ, about three inches in length, communicating below with the vagina by the cervical canal, and receiving the openings of the two Fallopian tubes, at either side, in its upper portion; it is lined with a thick mucous membrane which is shed at each menstrual period, and its cavity serves as the resting place in which the ovum, if impregnated, is harbored and developed for a period of ten lunar months two hundred and eighty days at the termination of which time it expels it as a full time child.
The Fallopian tubes, or oviducts, are two muscular canals which extend in a sinuous wavy manner from either side of the uterus at its upper part, outward toward the ovaries. Each is from four to five inches in length, and they are lined with a thick mucous membrane covered with ciliated epithelial cells, which by their lashing movements create a current toward the uterus.
At their outer extremities they are provided with finger like processes, ox fimbria, whose function is to grasp the ovaries on either side at the point from which the ripe ovum is about to escape, and these tubes serve to transmit the ova to the uterus.
In spite of the current which is established by the ciliated epithelium of the tubes toward the uterus, the spermatozoa, by their independent vibratory motions, force themselves contrary to it to the extreme limits of the Fallopian tubes, where fertilization of the ovum takes place.
The ovaries are a pair of germ glands situated in the pelvic cavity, one on either side, at the extremities of the Fallopian tubes.
They are analogous to the testicles of the male, since they develop the essential female reproductive element, or ovum, which when impregnated by a spermatozoon, develops into a foetus. (See "Female Genital Organs and Appendages, Fig. XL, page 305.)
Each ovary is a flattened ovoid body about one and one half inches in length and one-half inch in thickness, slightly varying in size at different times.
Each ovary contains upward of seventy thousand Graafian follicles, in each of which there is an ovum or egg cell.
The ovaries of a child a year old contain as many Graafian follicles with their contained ova as do those of the fully developed woman; but these ova do not begin to "ripen" until puberty, and even then only a small minority of the seventy thousand ever come to maturity.
Each ovum rests in a Graafian follicle, and as a rule but one of them ripens monthly. As the Graafian follicle with its enclosed ovum develops, it moves to the surface of the ovary and produces a protuberance, which finally ruptures and allows the ovum to escape into the Fallopian tubes.