DESCENT OF THE TESTIS. 



1295 



Vessels and Nerves of the Ductus Deferens and of the Vesicula Seminalis. The 



ductus deferens receives its arterial supply from the superior or inferior vesical artery. The 

 artery to the duct accompanies' that structure, supplying it as far as the testis, where it ends by 

 anastomosing with branches of the internal spermatic artery. The vesicula seminalis is supplied 

 by the inferior vesical artery. The nerves of the ductus deferens and vesicula seminalis are 

 derived from the hypogastric plexus. In lower animals the nerves for the seminal vesicles 

 are derived from the nerve roots of the second, third, and fourth lumbar nerves. 



DESCENT OF THE TESTIS. 



The peculiar course pursued by the ductus deferens in the adult, and the manner in 

 which it is related to the anterior abdominal wall, are rendered clear by a study of the 

 arrangement of the parts in the foetus. The testes until nearly the end of intra-uterine 

 life are placed in the abdominal cavity. Lying at first on the posterior wall of the abdomen 

 at the level of the upper two lumbar vertebrae, and just below the level assumed at 

 this time by the permanent kidney, the testis is held in place by a fold of peritoneum or 

 mesentery, called the mesorchium. As growth goes on the testis is found to occupy a 

 lower level in the abdominal cavity ; in the third month it lies in the iliac fossa, and in 

 the seventh it is situated 



Urinary bladder Umbilical artery 



Abdominal \~~52-^--^Jzr-/L 



inguinal ring /^\ " -J^.'A^Sv Testis 



Epididymis 



Gubernaculum 



Mesorchium 



Ductus 

 deferens 

 Internal sper- 

 matic vessels 



Psoas major 



Rectum 



PART OF THE ABDOMINAL CAVITY IN A FCETUS OF ABOUT THE 

 SEVENTH MoNTH ' 



( - )n 



represents a slightly more advanced condition than 

 the right, the testis has entered the inguinal canal ; on the right side 

 the testis is still within the abdominal cavity. 



near the abdominal inguinal 



ring. Meanwhile a blind 



pouch or diverticulum of 



the peritoneal membrane, 



termed the processus 



vaginalis peritonsei, has 



grown downwards and in- 



wards through the anterior Ductug 



abdominal wall towards the deferens 



scrotum, deriving as it goes 



a covering from each of the 



layers of the abdominal 



wall through which it 



passes. The testis with its 



mesorchium enters the 



diverticulum of the ab- 



dominal cavity, and de- FIG. 1014. VIEW LOOKING FROM ABOVE INTO THE PELVIS AND LOWER 



scends within it until the 



scrotum is reached. At a 



later stage the connexion 



between the part of the 



processus vaginalis that lies 



in the scrotum and the peritoneal lining of the abdomen becomes lost by the oblitera- 



tion of the upper part of the pouch. Thus the part of the processus vaginalis that 



persists in the scrotum becomes the parietal portion of the tunica vaginalis ; while the 



visceral part of that membrane is the primitive peritoneal covering of the testis and 



epididymis (Figs. 1014 and 1015). 



Often a small fibrous band the " ligamentum vaginale " may be found in the adult 

 passing through the inguinal canal and joining the peritoneum superiorly in the region of 

 the abdominal inguinal ring. Sometimes this band is connected below with the tunica 

 vaginalis, but more often it does not reach so far downwards. When present it represents 

 the obliterated portion of the processus vaginalis, ' and is therefore known as the 

 rudimentum processus vaginalis. 



In other rare cases the processus vaginalis may persist after birth as a channel freely 

 open to the abdominal cavity above, or the passage, becoming closed at intervals, may 

 give rise to one or more cysts within the coverings of the spermatic funiculus. 



It sometimes happens that the descent of the testis is arrested, and then, either 

 failing to enter the processus vaginalis, the testis remains within the abdominal cavity ; 

 or entering the processus vaginalis, it fails to reach the scrotum, and lies in the inguinal 

 canal. The term " cryptorchism " is frequently applied to such cases. 



In connexion with the descent of the testis a remarkable cord-like structure the 

 gubernaculum testis [Hunteri] must be mentioned. The gubernaculum arises for the 

 most part within a peritoneal fold which, at an early time in the development of the 

 foetus, may be seen stretching from the inguinal region to the Wolffian duct (future 

 duct of the testis) and inferior end of the mesonephros or primitive kidney. This peritoneal 



