THE UROGENITAL SYSTEM. 



453 



obliterated hypogastric artery, the obturator vessels and nerve, the vesical arteries, 

 from the inferior of which it receives the artery of the vas, and finally the ureter. In 

 its pelvic course the vas deferens is not often the subject of surgical interference 

 except in cases of undescended testis. In these cases it is often loosened from the 

 firm but thin fibrous bands which retain it in place, after which it is readily drawn 

 forward to allow the testicle to descend. 



DEVELOPMENT OF THE UROGENITAL SYSTEM. 



In the early stages of development of the human embryo there arises from the 

 parietal mesothelium on each side a tube known as the Wolffian duct with a collec- 

 tion of tubules known as the Wolffian body. This reaches its full development in the 

 seventh week. On one side of the Wolffian body develops the sexual gland, which 

 later becomes either a testicle or ovary. At the caudate extremity of the Wolffian 

 body develops the kidney by the end of the second month. At this time the bladder 

 is connected by the urachus with the stalk of the allantois. The lower end of the 

 bladder is connected with the extremity of the intestinal tract through a dilatation 



Hydaticl of Morgagni 



Testicle 



Epididymis 



Duct of Rathke 



( >rgan of Giraldes 



Gubernaculum 



Vas deferens 



Ureter 



Urachus 



Duct of Miiller 



atrophied 



Bladder 



linal vesicle 

 Kectu 



BEFORE DIFFERENTIATION MALE FEMALE 



FIG. 457. The development of the genital organs. 



called the urogenital sinus. The union of the urogenital sinus and intestine forms the 

 cloaca. At the time the Wolffian body is developing there appears alongside of it a 

 tube called the duct of Miiller. It atrophies in the male but in the female becomes 

 the Fallopian tube, uterus, and vagina. The ureter is developed and becomes con- 

 nected with the lower portion of the bladder (Fig. 457). 



The Wolffian duct and duct of Miiller, until about the third month, empty into 

 the urogenital sinus. Differentiation of the sexes begins about the third month and 

 is well advanced in the fifth. The sexual gland in the male becomes the testicle and 

 passing from its lower end is seen the gubernaculum. In the female it becomes the 

 ovary and the round ligament passes from its lower end. The Wolffian body after 

 performing temporarily the functions of a kidney disappears, leaving sometimes a small 

 cyst attached to the upper part of the epididymis.in the male and in the broad ligament 

 near the ovary in the female, known as the hydatid of Morgagni {stalked hydatid}. 

 Its lower portion has as its remains some short closed tubes in the tail of the epidid- 

 ymis known as the paradidymis or organ of Giraldes in the male and the paro- 

 ophoron of the broad ligament in the female. The Wolffian duct, while forming the 

 vas deferens and part of the epididymis in the male, forms the atrophied paroophoron 

 in the female to the inner side of the ovary. 



