[CHAPTER VIII]
THE FUNCTIONS OF THE FEMALE GENITAL ORGANS
Functions of the ovary.—The ovary is lined by a layer of genital epithelia (“Keimepithel”), which undergo certain changes during the entire sexual life of the woman. The epithelia are continually transformed into ova. When a single genital epithelium leaves the ovarian lining to be transformed into an ovum it moves from the periphery toward the centre. It then surrounds itself with follicular epithelia and forms the Graafian follicle. Through its growth the Graafian follicle approaches again the periphery. All ripe Graafian follicles are, therefore, situated near the periphery of the ovary.
Ovulation.—About once a month a general congestion of the entire genital system takes place.[F] This congestion causes an effusion of serum and blood into the Graafian follicle and the rupture of the same. In this way the ovum is set free and is seized by the fimbriae of the Fallopian tube. The ovum begins now its journey towards the uterus. During its progress through the oviduct the maturition of the ovum, or the reduction of its chromosomes to half the number peculiar to its species, takes place by a double segmentation. The ovum is divided, twice in succession, each time into two quite unequal parts. The smaller segments, called polar bodies, remain near the periphery of the ovum and are extruded later on. The ovum is now ripe for fertilization.
According to Bischoff and Hiss, the impregnation takes place in the distal end of the tube. After impregnation the zygote continues its wandering by the current of the ciliated epithelia of the tube, towards the uterus. The ovum needs, according to Hensen, from three to five days, according to Bischoff eight days, to transverse this way, in the woman. It could not last any longer, says Von Winckel, because the uterine end of the tube, in the human female, has a diameter of only two to three millimeters, while the diameter of the ovum, in the second week of pregnancy, is three to six millimeters already. Hence, when a retardation, for one cause or another, takes place, a tubal pregnancy will be the result.
When the impregnated ovum has reached the cavity of the uterus it penetrates through the epithelium into the submucous fibrous tissues of the uterus, where it completes its development.
Internal ovarian secretion.—Besides the function of preparing the ova, the ovary has an internal secretion which is the cause of the female secondary characteristics. When both ovaries are removed before puberty, the time when the stamp of sex is becoming impressed on every part of the body, the essential feminine features fail to develop. The absence of the ovaries leads to the development of a colorless, neuter creature of angular form, strident voice, striding gait, and even of bearded chin.
Function of the Fallopian tubes.—The function of the ducts is to furnish a path for the ovum in its passage towards the uterus and for the spermatozoa on their way to meet the ovum. The current of the tubal ciliated epithelia is directed towards the uterus. In this way the ovum which does not possess self-motion, as do the spermatozoa, is carried towards its destination, while the spermatozoa have to swim against the current.
Menstruation.—The main function of the uterus is to serve as a couch or resting place for the fertilized ovum during its development. For this end a wound has to be set in the lining of the uterus to facilitate the grafting of the fertilized ovum, just as the gardner makes a slit for ingrafting the young shoot. The preparation of the ingrafting of the young animal is accomplished by the monthly changes in the uterus preceding menstruation. The monthly general congestion of the genital organs, necessary for the ovum to leave the Graafian follicle, also causes the uterine mucous membrane to swell from one to three millimeters in the thickness.[G] The mucosa becomes thus turgid and velvety. The epithelial cells of the endometrium swell and multiply. The openings of the uterine glands are enlarged, and a whitish, opaque mucus is poured out. The glandular cells are enlarged, and there is a multiplication of the round cells of the stroma. The cells are cloudy and filled with fat granules. This fatty degeneration involves the glandular cells, the cells of the inter-glandular tissue, and the cells of the blood vessels which are distended with blood. The endometrium or lining is thus prepared for the reception of the impregnated ovum. These alterations develop independently of the haemorrhage. The swelling begins a long time before the period and reaches its maximum only at this time.
If the ovum has become impregnated it is ready to respond to these preparations. If, however, nature’s attempt to reproduce an individual of the species has been frustrated, and the ovum has not been impregnated, the latter has to be cast out, and all the preparations are eliminated. The exuberant epithelial cells are exfoliated. The delicate capillaries, engorged with blood, sweat drops of blood by diapedesis or burst and discharge their contents. The congested and engorged glands secrete and excrete profusely.