1212 EMBRYOLOGY. 



develops, the lower end of the gubernaculum is carried with the skin to which it 

 is attached to the bottom of this pouch. The fold of peritoneum, constituting the 

 processus vaginalis, projects itself downward into the inguinal canal, and emerges 

 at the external abdominal ring, pushing before it a part of the internal oblique 

 muscle and the aponeurosis of the external oblique, which form, respectively, the 

 cremaster muscle and the external spermatic fascia. It forms a gradually elon- 

 gating depression or cul-de-sac, which eventually reaches the bottom of the scrotum, 

 and into this the testicle is drawn by the growth of the body of the foetus, for the 

 gubernaculum does not grow commensurately with the growth of other parts, and 

 therefore the testicle, being attached by the gubernaculum to the bottom of the 

 scrotum, is prevented from rising as the bottom grows, and is drawn first into the 

 inguinal canal and eventually into the scrotum. It seems certain also that the 

 gubernacular cord becomes shortened as development proceeds, and this assists in 

 causing the testicle to reach the bottom of the scrotum. By the eighth month the 

 testicle has reached the scrotum, preceded by the lengthened pouch of peritoneum, 

 the processus vaginalis, which communicates by its upper extremity with the peri- 

 toneal cavity. Just before birth the upper part of the pouch usually becomes 

 closed, and this obliteration extends gradually downward to within a short distance 

 of the testis. The process of peritoneum surrounding the testis, which is now 

 entirely cut off from the general peritoneal cavity, constitutes the tunica vaginalis. 1 

 In the female there is also a gubernaculum, which effects a considerable change 

 in the position of the ovary, though not so extensive a change as that of the testicle 

 in the male. The gubernaculum in the female, as it lies on either side in contact 

 with the fundus of the uterus formed by the union of the Miillerian ducts, con- 

 tracts adhesions to this organ, and thus the ovary is prevented from descending 

 below this level. The remains of the gubernaculum that is to say, the part 

 below the attachment of the cord to the uterus to its termination in the labia 

 majora ultimately forms the round ligament of the uterus. A pouch of peritoneum 

 accompanies it along the inguinal canal, analogous to the processus vaginalis in 

 the male ; it is called the canal of Nuck. In rare cases the gubernaculum may 

 fail to contract adhesions to the uterus, and then the ovary descends through the 

 inguinal canal into the labia majora, extending down the canal of Nuck, and 

 under these circumstances resembles in position the testicles in the male. 



Surgical Anatomy. Abnormalities in the formation and in the descent of the testicle 

 may occur. The testicle may fail to be developed ; or the testicle may be fully developed, and 

 the vas deferens may be undeveloped in whole or part ; or, again, both testicle and vas deferens 

 may be fully developed, but the duct may not become connected to the gland. The testicle 

 may fail in its descent, or it may descend into some abnormal position. Thus it may be retained 

 in the position where it was primarily developed, below the kidney ; or it may descend to the 

 internal abdominal ring, but fail to pass through this opening ; it may be retained in the inguinal 

 canal, which is perhaps the most common position ; or it may pass through the external abdom- 

 inal ring and remain just outside it, failing to pass to the bottom of the scrotum. On the other 

 hand, it may get into some abnormal position : it may pass the scrotum and reach the peri- 

 neum, or it may fail to enter the inguinal canal, and may find its way through the femoral ring 

 into the crural canal, and present itself on the thigh at the saphenous opening. There is still a 

 third class of cases of abnormality of the testicle : where the organ has descended in due course 

 into the scrotum, but is malplaced. The most common form of this is where the testicle is 

 inverted; that is to say, the organ is rotated so that the epididymis is connected to the front of 

 the scrotum, and the body, surrounded by the tunica vaginalis, is directed backward. In these 

 cases the vas deferens is to be felt in the front of the cord. The condition is of importance in 

 connection with hydrocele and hsematocele, and the position of the testicle should always be 

 carefully ascertained before performing any operation for these affections. Again, more rarely, 

 the testicle may be reversed. This is a condition in which the top of the testicle, indicated by 

 the globus major of the epididymis, is at the bottom of the scrotum, and the vas deferens 

 comes off from the summit of the organ. Cases sometimes occur, generally in the young adult, 

 in which the spermatic cord becomes twisted. In consequence of this the circulation through it 

 is partially or completely arrested ; if the latter, the testicle becomes gangrenous ; if the former, 

 it may undergo atrophy. 



The external organs of generation (Fig. 780), like the internal, pass through 



1 The obliteration of the process of peritoneum which accompanies the cord, and is hence called 

 the funicular process, is often incomplete. See section on Inguinal Hernia. 



