1314 THE UEO-GENITAL SYSTEM. 



tube-like processes, or " egg tubes." This takes place during foetal development, and the 

 branching cellular processes so formed become broken up, within the stroma, into little 

 nests or clumps of cells, each of which becomes a vesicular follicle. From the beginning 

 some cells of the egg tubes are larger than the others ; these become the future ova, 

 while the cells round them become the investing cells of the follicle. The investing cells, 

 at first flattened, form a single layer round each ovum. Later, becoming columnar, as the 

 follicle increases in size and sinks more deeply in the stroma, these cells divide in such a 

 manner that the ovum becomes surrounded by a double layer of cells. Fluid liquor 

 folliculi accumulates between the two cellular layers, except at one place where the 

 inner cells surrounding the ovum remain attached to the outer layer or stratum granu- 

 losum. To the inner cellular mass Enclosing the ovulum, or ovum, the term cumulus 

 oophorus (O.T. discus proligerus) is applied (Fig. 1031). The ripe follicle contains a rela- 

 tively large amount of fluid, and the surrounding stroma becomes differentiated to form 

 for it a theca folliculi, or capsule. This capsule is composed of an inner more vascular 

 layer, the tunica interna, and an outer more fibrous layer, the tunica externa. There is 

 reason to believe that in the human subject the formation of ova and follicles ceases 

 before birth, and that the appearances which have led to the belief that they may 

 originate during the first years of extra-uterine life have been due to pathological con- 

 ditions. In the young child there are enormous numbers of small follicles in the super- 

 ficial parts of the ovary, but in old age none are found in this situation. 



The appearance and structure of the ripe ova are described on pp. 13-16. 



Vessels and Nerves of the Ovary. The ovarian arteries, corresponding to the internal 

 spermatic arteries of the male, are a pair of long slender vessels which spring from the anterior 

 aspect of the aorta, below the level of origin of the renal vessels. Each gains the pelvis in the 

 fold of peritoneum forming the suspensory ligament of the ovary, and enters the ovary at its ; 

 mesovarian border, or hilum. The ovarian artery anastomoses freely, near the hilum, with 

 other vessels, derived from the uterine arteries. The blood is returned by a series of communicat- j 

 ing veins, similar to the plexus pampiniformis in the male. 



The nerves of the ovary are derived chiefly from a plexus which accompanies the ovarian 

 artery, and which is continuous above with the renal plexus. Other fibres are derived from the 

 inferior part of the aortic plexus, and join the plexus on the ovarian artery (plexus arteriae 

 ovaricae). The afferent impulses from the ovary reach the central nervous system through the 

 posterior root fibres of the tenth thoracic nerve. 



The lymph-vessels of the ovary join with those from the upper part of the uterus, and end 

 in the lumbar lymph-glands. 



TUB.E UTERINE. 



The uterine tubes (O.T. Fallopian tubes) are a pair of ducts or passages which 

 convey the ova, discharged from the vesicular follicles of the ovaries, to the cavity of 

 the uterus. Each tube is about four and a quarter inches in length, and opens at one 

 end into the pelvic cavity near the ovary, and at the other end by a smaller opening 

 into the lateral part of the uterine cavity. The tube is enclosed in a fold of peri- 

 toneum called the mesosalpinx, which is a portion of the broad ligament of the uterus. 



The opening of the tube into the pelvic cavity or ostium abdominale is of j 

 small size, being only about 2 mm. in diameter when its walls are relaxed, and 

 much narrower when the muscular coat of the tube is contracted. This opening is 

 placed at the bottom of a funnel-like expansion of the tube called the infundibulum 

 tubae uterinas, the margins of which are produced into a number of irregular processes 

 or fimbriae tubas. The presence of these fimbrise, many of which are branched or : 

 fringed, has given the name fimbriated extremity to this end of the uterine tube. 

 The surface of the fimbrige which looks into the cavity of the infundibulum is 

 covered by a mucous membrane continuous with that lining the tube, while the 

 outer surface is clothed by peritoneum. The mucous surfaces of the larger fimbriae 

 present ridges and grooves which are continued into the folds and furrows of the 

 mucous coat of the tube. One of the fimbriae, usually much larger than the rest, is j 

 connected either directly or indirectly with the tubal extremity of the ovary, and 

 it the name fimbria ovarica, or ovarian fimbria, is applied. The part of the tube 

 continuous with the infundibulum, and into which the ostium abdominale leads, is 

 called the ampulla tubas uterinse. This, the widest and longest portion of th( 

 uterine tube, is usually tortuous and of varying diameter, being in some pi 

 slightly constricted, and in others distended. The wide, thin -walled arnpi 

 ends in the narrower, thicker -walled, and much shorter isthmus tubas utei 



