Fig. [15].—Primitive follicles.
In the further course of development of the graafian follicles at this period, the most advanced now reapproach the surface of the ovary, so that a fully-matured follicle comes to occupy almost the entire thickness of the cortical substance, and may even give rise to a localized bulging of the surface of the organ. In such a mature follicle, which has attained nearly the size of a pea, we recognize an outermost connective-tissue investment (theca folliculi), consisting of condensed ovarian stroma, in which two layers are distinguished, sometimes called simply outer tunic and inner tunic, sometimes known by the names of tunica fibrosa (outer) and tunica propria (inner), respectively; within this is the cellular layer known as the membrana granulosa (or stratum granulosum), the portion of which, now greatly enlarged, immediately surrounding the ovum is known as the discus proligerus (or cumulus oöphorus); the interspace between the discus proligerus and the membrana granulosa is filled with a clear fluid, the liquor folliculi. In consequence of the continued increase in its fluid contents, the graafian follicle ultimately bursts along the most prominent portion of the superficial wall, and the ovum passes out through the rupture, finding its way under normal conditions into the Fallopian tube and through this into the uterus. The follicle itself then undergoes a regressive metamorphosis, forming the corpus luteum, the rent in the envelope of which, after the absorption of the yellowish semi-fluid contents, undergoes cicatrization. Contemporaneously with this development at puberty of the process of ovulation, menstruation also for the first time makes its appearance, recurring thenceforward at four-weekly intervals as the regular catamenial discharge.
We append the account given by Pfannenstiel regarding the ovarian follicles. He writes: “In correspondence with the especial function of the female reproductive gland, which is to bring to maturity and to evacuate only after the lapse of a considerable period and at successive intervals, the ova which it has contained from the very outset, we find that primitive follicles continue to exist in the ovary up to the very end of the period of sexual activity, though naturally in diminishing numbers; and the size and shape of these primitive follicles remain nearly identical throughout the various periods of life. As the follicle ripens, the epithelium grows, the cells becoming cubical with a rounded nucleus, and increasing in number by cell-division, so that several layers are formed. As soon as these layers are three or four in number, a space, at first slit-shaped, forms in the epithelium on the peripheral surface of the ovum; this space is filled with fluid, known as the liquor folliculi; the peripheral layer of cells, the membrana granulosa, is thus separated from the mass of epithelial cells immediately enveloping the ovum, the discus proligerus, which is situate in the side of the follicle adjacent to the hilum of the ovary. By the increase of the liquor folliculi the graafian follicle is formed, a vesicle the envelope of which is formed by the multilaminar membrana granulosa, whilst in the pole of the vesicle directed toward the hilum ovarii is the ovum imbedded in the mass of cells forming the discus proligerus, a mass which has the form of a truncated cone. The liquor folliculi is formed by the epithelium, the nuclei of which disappear by chromatolysis or by simple atrophy whilst the cell-bodies liquefy in consequence of albuminous, not fatty, degeneration (Schottländer). Within the epithelium of the follicle we find the faintly glistening epithelial vacuoles of Fleming, likewise cells which liquefy and assist in increasing the bulk of the liquor folliculi. This liquor is a thin, serous fluid, and contains albumin. * * * Every graafian follicle has a bilaminar investing membrane, which is formed by the ovarian stroma. * * * The ovum of the growing follicle increases in size very slowly indeed, attaining on the average, according to Nagel, a diameter of 165 to 170 µ, it retains its zona pellucida, the greater part of the protoplasm of the cell is transformed into deutoplasm (food-yolk, or yolk-granules), the nucleus assumes an eccentric position. Between the zona pellucida and the cell-body a narrow perivitelline space appears. The ovum is then full-grown, but not yet fully prepared for fertilization; for this, maturation is required, certain changes in the germinal vesicle, which occur after the bursting of the follicle. * * * As a rule each follicle contains a single ovum. But two and even three ova have beyond doubt been observed in one follicle.”
According to Waldeyer, the bursting of the follicle is not to be regarded as dependent upon a sudden rise of pressure in its interior, but as the result of a gradual ripening process. At the deepest pole of the follicle, which in the course of its development has now approached the surface of the ovary, an exuberant growth takes place in the internal layer (tunica propria) of the theca folliculi, with a profuse formation of new vessels. Here numerous “epithelioid” cells, the “lutein-cells,” make their appearance. In consequence of this proliferation of the lutein-cells, the contents of the follicle are gradually pressed toward the “stigma,” the superficial pole of the follicle, and the follicle itself is pushed toward the surface until it finally comes into contact with the germinal epithelium. Meanwhile the follicular epithelium undergoes fatty degeneration, alike in the membrana granulosa and in the discus proligerus. In consequence of the proliferation of the lutein-cells, on the one hand, and the fatty degeneration of the epithelium, on the other, the follicle opens at its weakest point, the stigma, and the ovum is extruded, with the liquor folliculi, and a number of cells belonging to the follicular epithelium. (To illustrate these changes we have borrowed Figs. 15, 16, and 17 from the monograph, by Pfannenstiel on Diseases of the Ovary, in J. Veits’ Handbook of Gynecology.)
The ovaries, which in the new-born female infant are flattened, ribbon-like bodies one-half to one centimeter (0.2 to 0.4″) in length, and in childhood are cylindrical, with a perfectly smooth surface, assume at the time of puberty a more or less flattened form. During the menarche they have an elongated oval shape, flattened from side to side, their average length being 2.5 to 5.0 centimetres (1 to 2″), width 1.5 to 3.0 centimetres (0.59 to 1.18″), thickness 0.6 to 1.4 centimetres (0.24 to 0.55″), weight 5 to 8 grammes (77 to 123 grains). After the repeated occurrence of ovulation, the surface of the ovary becomes more and more uneven, being thickly covered with fossæ or scar-like fissures.
Fig. [16].—Ripening follicles.
The vagina during virgin girlhood is narrow, and its mucous surface is beset with numerous rugæ, which may be plainly felt as well as seen. The calibre of the vagina is proportionately less the younger the girl. The examining finger is gripped by the vaginal wall as by an india-rubber tube (Maschka). The vaginal portion of the cervix is felt in the form of a truncated cone, with a smooth surface, rather dense in consistence; the external os opens at the bottom of a small depression on its surface, in the form of a short oval, the long axis of which is transversely directed. Shortly before the menarche, Bartholin’s glands become noticeable on either side of the lower end of the vagina between the sphincter muscles.
The clitoris in many cases attains a very large size, and this is apt to lead to sexual malpractices. According to Hyrtl, in southern countries the clitoris is larger than in temperate and cold climates. In the women of Abyssinia and among the Mandingoes and the Ibboes, the size is portentous, and amongst the first-named, circumcision of females is a customary operation. It is said that female slaves belonging to these races are greatly esteemed by the ladies of the harem, and are eagerly sought for. In the anatomicopathological museum at Prague there is a preparation of the female genital organs with a clitoris as large as the penis of a full-grown man.