562 DESCENT OF THE TESTICLE. 



The Descent of the testicle is very gradual and progressive. 

 Between the fifth and sixth month it has reached the lower part of 

 the psoas muscle, and during the seventh it makes its way through 

 the spermatic canal, and descends into the scrotum. 



While situated in the lumbar region, the testis and gubernaculum 

 are placed behind the peritoneum, by which they are invested upon 

 their anterior surface and sides. As they descend, the investing 

 peritoneum is carried downwards with the testis into the scrotum, 

 forming a lengthened pouch which by its upper extremity opens 

 into the cavity of the peritoneum. The upper part of this pouch 

 being compressed by the spermatic canal is gradually obliterated, 

 the obliteration extending downwards along the spermatic cord 

 nearly to the testis. That portion of the peritoneum which imme- 

 diately surrounds the testis is, by the above process, cut off from its 

 continuity with the peritoneum, and is termed the tunica vaginalis ; 

 and as this membrane must be obviously a shut sac, one portion of 

 it investing the testis, and the other being reflected so as to form a 

 loose bag around it, its two portions have received the appellations 

 of tunica vaginalis propria, and tunica vaginalis reflexa. 



The descent of the testis is effected by means of the traction of the 

 muscle of the gubernaculum (eremaster). " The fibres," writes Mr. 

 Curling,* " proceeding from Poupart's ligament and the obliquus 

 internus, tend to guide the gland into the inguinal canal ; those 

 attached to the os pubis, to draw it below the abdominal ring ; and 

 the process descending to the scrotum, to direct it to its final des- 

 tination." During the descent " the muscle of the testis is gra- 

 dually everted, until, when the transition is completed, it forms a 

 muscular envelope external to the process of peritoneum, which 

 surrounds the gland and the front of the cord." " The mass com- 

 posing the central part of the gubernaculum, which is so soft, lax, 

 and yielding as in every way to facilitate these changes, becomes 

 gradually diffused, and, after the arrival of the testicle in the 

 scrotum, contributes to form the loose cellular tissue which after- 

 wards exists so abundantly in this part." The attachment of the 

 gubernaculum to the bottom of the scrotum is indicated throughout 

 life by distinct traces. 



* Loc. cit. 



