Plica phrenico 

 mesonephrica 



Sexual gland 



Wolffian body 



Wolffian 

 duct 



DEVELOPMENT OF THE REPRODUCTIVE ORGANS. 2041 



inguinal ligament, corresponds with the gubernaculum testis in the male and with the 

 round ligament of the uterus in the female. In the former it is not directly attached 

 to the testis, but only through its ligament, the point of attachment later corre- 

 sponding to the origin 



of the vas deferens FIG. 1720 



from the epididymis. 



The testicle begins 

 its descent during the 

 second foetal month, 

 coincidently with com- 

 mencing atrophy of the 

 Wolffian body, and, 

 under the influence and 

 guidance of the genito- 

 inguinal ligament, by 

 the end of the third 

 month reaches the an- 

 terior abdominal wall 

 in the vicinity of the 

 later internal abdomi- 

 nal ring. This position 

 it retains until the close 

 of the sixth month, 

 when it enters upon its 

 final descent. 



Meanwhile, the 

 musculo-fascial layers 

 of the abdominal wall undergo evagination, resulting in the production of a shallow 

 pouch, the inguinal bursa, into which a sac of peritoneum, the processiis vaginalis, 

 extends, together with the closely associated genito-inguinal ligament. The inguinal 

 bursa, in turn, sinks into the shallow scrotal pouch that has independently devel- 

 oped as an integumentary fold. The wall of the bursa contains the constituents that 

 later differentiate into the coverings proper of the spermatic cord and testicle the 

 intercolumnar, cremasteric, and infundibuliform fasciae. Its muscular fibres, pro- 

 longed from the internal oblique and transversalis layer, correspond with the cre- 

 master, and surround the genito-inguinal ligament. 



Owing to the thickening of the lower end of the latter, a slight elevation appears 

 on the floor of the bursa, which thus seemingly becomes pushed up towards the 

 testis to form the rudiment of what in some animals becomes a well-marked projec- 

 tion, the conus ingualis, but in man always remains insignificant. In consequence 

 of these changes, during the fourth month the testis is displaced upward and its 



descent temporarily inter- 

 FIG. 1721. 



^ Epididymis 

 Testis 



Yas deferens 



Deep epigastric vessels 



Mesentery of 



gland 



Wolffian duct 



Genito-inguina! 

 ligament 



Plica inguina 

 mesonephrica 



Ligament of gland 



Umbilical arteries 



Gut 



Allantoic duct 

 Umbilical vein 



Wolffian bodies and sexual glands of human embryo of about six weeks 

 (17 mm. long). X 15. (Modified from Kollmann.) 



Peritoneal cavitv 



Int. obi 

 Aponeim 



and transv 

 is of extei 



rupted. 



About the beginning of 

 the seventh month, the final 

 descent of the testicle is in- 

 augurated with deepening 

 of the bursa and downward 

 extension of the peritoneal 

 pouch, accompanied by the 

 now thickened and short- 

 ened genito-inguinal liga- 

 ment. Although shorten- 

 ing of the latter, together 

 with the pull exerted by the 

 cremasteric fibres, plays an active role in drawing the testicle through the abdominal 

 wall and into the scrotum, these factors are undoubtedly supplemented by forces result- 

 ing from the growth and expansion of the pelvis and inguinal regions. 



The processus vaginalis reaches the bottom of the scrotal sac in advance of the 



.muscles-^ 

 il oblique 

 Peritoneum 

 Genito-inguinal ligament 



Transversalis fascia 



Cremaster muscle ~ 



Intercolumnar fascia - 



Integumentary scrotal pouch 



Rectus muscle 



Processus vaginalis 

 Attachment of ligament to 

 lickened floor of inguinal 



Diagram showing early stage in descent of testicle. (After Waldeyer.) 



