OVULATION. MENSTRUATION.
These two functions are considered as one, the last being the external manifestation of the first. We will see that, during the last few years, a number of authors tend to oppose this view.
By ovulation we mean those phenomena which occur in the ovary, and which consist in the maturing, the rupture of the Graafian vesicle, and the departure of the ovum from the vesicle. This last is followed by the migration of the ovum, and the cicatrization of the Graafian vesicle, or the production of what is called the corpus luteum.
Maturation and Rupture of the Graafian Vesicle.
We have seen that, until puberty, the Graafian vesicles form the ovi genetic layer of the ovary (Figs-58, 59, 60), which is then smooth and uniform.
At the beginning of this period, fifteen or twenty of these vesicles de velop much more than the others. One of these especially seems to at tract all the productive activity; it develops to a considerable extent, forms a more and more marked projection on the surface of the ovary, which it continually approaches,, and finally becomes almost as large as a cherry. Under the influence of this development, the vessels of this vesicle, which are lengthened and compressed by this distension, become atrophied, and even obliterated at the highest point (Fig 61). Its wall grows gradually thinner, finally to burst, and the ovum, forced from the ovary, is received by the pavilion of the tube. This phenomenon, which is reproduced every month, constitutes spontaneous ovulation. There occurs here a phenomenon analogous to that which happens at the rup ture of an acute abscess.
The liquid which the vesicle of de Graaf normally contains, gradually in creases, and flows into the cavity of the ovisac, thus distending and thin ning its walls more and more, which, having reached the limit of their re sistance, give way and burst, allowing the liquid and the ovum to escape. This requires a space of time that varies generally between six and eight days, and is accompanied by a swelling, a marked tumefaction of the ovary on the side where the vesicle developed. The researches of Puech, Depaul and Gui.niot, leave no doubt of this.
The height and thickness of the organ are especially modified. This developement of the ovary is due to the congestion, which is produced in the ovary at the time of evolution of the follicle; and this congestion is greater when the follicle that develops is deeply situated, and has a longer path to traverse in order to reach the surface of the ovary. In certain cases blood effusions are produced either in the hypertrophied vesicle, or in the neighboring ovisacs, or in the bulk of the ovary. Again, the rup ture of the vesicle of de Graaf may take place in a slow and gradual man ner. The true membranes are first torn, and it always results from this that a small bloody extravasation occurs at their summit. The peri toneum yields last, but it is very rare that this hemorrhage is sufficient to form a clot capable of filling the follicle of de Graaf. Ordinarily, it is
limited to slightly tinting the fluid that effuses in the vesicle after the expulsion of the ovum.
Migration of the Ova.
At the moment when the Graafian vesicle ruptures and allows the ovum to escape, the tube is applied to the ovary, and surrounds it with its pavilion; hence the ovum penetrates the pavilion, and from there passes into the canal of the tube, which conducts it to the uterus.
According to the older authors,—Haller at their head,—this adaptation of the tube to the ovary is due to the contraction of muscular fibres sit uated within the walls of that organ. Many of them, struck by the vio let color of the tube, and by its hyperaemia at the time of menstruation, admit a true erection of the tube. According to Rouget this fluxion is not sufficient, and he explains this adaptation by the direction of the muscular fibres, which he discovered and studied, in the ovary, the tube and the pavilion. The ovum, seized by the pavilion, is thus forced into the tube by the contraction of these muscular fibres. This explanation does not satisfy modern writers, and each one has given one of his own. Although Kehrer, and Liegeois regard this phenomenon as a true ejec tion from the ovary, which throws the ovum into the pavilion, just as the semen is thrown into the vagina, yet, according to Kiwisch and Schroeder, the cells of cylindrical epithelium with vibratile cilia, which the tube possesses at its abdominal extremity, establish around that orifice, and in the serous fluid that continually lubricates the peritoneum, a continu ous current capable of carrying with it particles as small as an ovum. The existence of this serous current has been demonstrated by Becker. If, on the contrary, the ovum does not reach the interior surface of the pavilion, it is lost in the abdominal cavity, and this explains the so-often negative results of sexual intercourse, and extra-uterine pregnancy. Ac cording to Schroeder, this serous current may be strong enough to carry the ovum, expelled from one ovary, to the tube of the opposite side. This is what is called external migration of the ovum. These external migra tions take place in cases of deviation or of obliteration of one of the tubes by inflammation, which has brought about adhesions or the production of false membranes. The cases of Rokitanski, Czihak, Luschka, Drejer, Scanzoni, Oldham, etc., confirm this theory. Leopold, of Leipzig, studied this question, and, after having repeated the experiments of Parsenow, and discussed the known facts, he arrives with Kussmaul at the follow ing conclusions: The ovum, ejected by the ovary of one side, may enter the tube of the opposite side, when the vibratile current of this latter carries it towards the ovary which ejected the ovum. The contact of the two organs is not indispensable for the migration of the ovum, for the vibratile current acts from a distance.