408 



ABDOMEN 



traced as far as the testis, but more commonly it only 

 extends down the cord for a short distance ; indeed it is 

 frequently absent. 



To obtain a proper conception of this fibrous thread, it is necessary that 

 the student should understand that neither the testis nor the tunica 

 vaginalis are developed in the scrotum. In the early months of foetal life 

 the rudimentary scrotum is devoid both of tunica vaginalis and testis, and 



Ductus deferens 

 Testicl 



Peritoneum 

 / Testicle 



Gubernaculum - 



Ductus deferens 

 Testicle 



Processus vaginalis 



Skin of scrotum 



Gubernaculum 



Ductus deferens 

 and peritoneum 



Skin of scrotum 

 Processus vaginalis 

 Gubernaculum 



Peritoneum 

 Ductus deferens 



Closed part of prc 

 cessus vaginalis 



- Testicle 



- Tunica vaginalis 

 Gubernaculum 



FIG. 152. Diagrams illustrating the descent of the Testis and the deriva- 

 tion of the tunica vaginalis from the peritoneal lining of the abdominal 

 cavity. 



the testis lies on the posterior wall of the abdomen projecting forwards 

 into the great serous cavity of the abdomen which is called the peritoneal 

 cavity. The wall of the peritoneal cavity is formed by a membrane 

 called the peritoneum, and the inner surface of the membrane is lined 

 by a layer of flat epithelium, peritoneal epithelium. The peritoneum which 

 is in contact, externally, with the general muscular wall of the abdomen 

 is called the parietal peritoneum ; but here and there the posterior wall of 

 the peritoneal sac is invaginated by one or other of the abdominal viscera. 

 When the invaginating viscus carries forward more peritoneum than is 

 necessary to cover its surface the excess of peritoneum forms a fold which 

 connects the viscus with the posterior wall of the abdomen ; such folds are 

 called mesenteries and they connect the peritoneum covering the invaginat- 

 ing viscus, which is termed the visceral peritoneum, with the parietal 



