770 EMBRYOLOGY 



who drowned herself four or five days after the cessation of the menses, 

 a follicle was found in the right ovary, so distended that it was ruptured 

 by very slight pressure ; and other instances were observed in which 

 follicles were not ruptured during the menstrual period. 



PASSAGE OF OVA INTO THE FALLOPIAN TUBES 



The fact that the ova in the great majority of instances pass into the 

 Fallopian tubes is sufficiently evident. The fact, also, that ova may fall 

 into the cavity of the peritoneum is illustrated by the occasional occur- 

 rence of extra-uterine pregnancy, a rare accident, which shows that in all 

 probability the failure of unimpregnated ova to enter the tubes is excep- 

 tional. As regards the mechanism of the passage of the ova into the 

 tubes, however, the explanation is difficult. At the present time there 

 are two theories in regard to this process ; one, in which it is supposed 

 that the fimbriated extremities of the Fallopian tubes, at the time of 

 rupture of the Graafian follicles, become adapted to the surface of the 

 ovaries, and the other, that the ova are carried to the openings of the 

 tubes, by ciliary currents. Neither of these theories, however, is sus- 

 ceptible of actual demonstration ; and their value is to be judged from 

 anatomical facts. It is not difficult to understand, taking into account 

 the situation of the ovaries and the relations of the Fallopian tubes, how 

 an ovum may pass into the tube, without invoking the aid of muscular 

 action. It may be supposed, for example, that a Graafian follicle is 

 ruptured when the fimbriated extremity of the tube is not applied to the 

 surface of the ovary. One of the fimbriae, longer than the others, is 

 attached to the outer angle of the ovary and presents a little furrow, or 

 gutter, leading to the opening of the tube. This furrow is lined with 

 ciliated epithelium, as, indeed, is the mucous membrane of all the fim- 

 briae, the movements of which produce a current in the direction of the 

 opening, which would apparently be sufficient to carry the ovum into the 

 tube. At the same time there probably is a constant flow of liquid over 

 the ovarian surface, directed by the ciliary current toward the tube ; and 

 when the liquid of the ruptured follicle is discharged this, with the ovum, 

 takes the same course. This probably is the mechanism of the passage 

 of ova into the Fallopian tubes ; and it is possible that the fimbri- 

 ated extremity may be drawn toward the ovarian surface, although it is 

 difficult to understand how it can be closely applied to the ovary and 

 exert any considerable pressure on the distended follicle. It is proper 

 to note, also, that the conditions dependent on the currents of liquid 

 directed by the movements of cilia are constant and could influence the 

 passage of an ovum at whatever time it might be discharged, while a 



