DEVELOPMENT OF THE GENITO-URINARY SYSTEM 837 



but the testicles, which are at first in the abdomen of the male, finally 

 descend into the scrotum. As the testicles descend they carry with 

 them the Wolffian duct, that portion of the Wolffian body which is per- 

 manent constituting the head of the epididymis. At the same time a 

 cord appears, attached to the lower extremity of the testicle and extend- 

 ing to the symphysis pubis. This is the gubernaculum testis. It is at 

 first muscular, but the muscular fibres disappear during the later periods 

 of utero-gestation. It is not known that its muscular structure takes any 

 part, by contractile action, in the descent of the testicle in the human 

 subject. The epididymis and the vas deferens are formed from the 

 Wolffian duct. 



At about the end of the seventh month the testicle has reached the 

 internal abdominal ring ; and at this time a double tubular process of 

 peritoneum, covered with a few fibres from the lower portion of the 

 internal oblique muscle of the abdomen, gradually extends into the 

 scrotum. The testicle descends, following this process of peritoneum, 

 which latter becomes eventually the visceral and parietal portions of the 

 tunica vaginalis. The canal of communication between the abdominal 

 cavity and the cavity of the scrotum is finally closed and the tunica 

 vaginalis is separated from the peritoneum. The fibres derived from 

 the internal oblique constitute the cremaster muscle. 



At the eighth or the ninth month the testicles have reached the exter- 

 nal abdominal ring and soon after descend into the scrotum. The vas 

 deferens passes from the testicle, along the base of the bladder, to open 

 into the prostatic portion of the urethra ; and as development advances, 

 two sacculated diverticula from these tubes make their appearance, 

 which are attached to the bladder and constitute the vesiculae seminales. 



As the ovaries descend to their permanent situation in the pelvic 

 cavity, there appears, attached to the inner extremity of each, a rounded 

 cord, analogous to the gubernaculum testis. A portion of this, connect- 

 ing the ovary with the uterus, constitutes the ligament of the ovary ; 

 and the inferior portion forms the round ligament of the uterus, which 

 passes through the inguinal canal and is attached to the symphysis 

 pubis. 



Development of the Urinary Apparatus. Behind the Wolffian bodies, 

 and developed independently of them, the kidneys, suprarenal capsules 

 and ureters make their appearance. The kidneys are developed in the 

 form of small rounded bodies, composed of short blind tubes, all con- 

 verging toward a single point, which is the hilum. These tubes increase 

 in length, branch, become convoluted in a certain portion of their extent, 

 and they finally assume the structure and arrangement of the renal 

 tubules, with their Malpighian bodies, bloodvessels etc. They all open 



