THE TESTICLE AND EPIDIDYMIS 457 



duct. The epididymis is a convoluted canal whose lumen is 

 continuous with that of the vas deferens. 



The tunica vaginalis is a closed serous sac, and consists of 

 a visceral layer and a parietal layer. 



The visceral layer adheres to the outer surface of the tunica 

 albuginea, surrounding the testis and epididymis, and joining 

 them together by a fold. It forms between them the pouch 

 known as the digital fossa. 



The parietal layer is reflected to the inner surface of the 

 scrotum at the posterior border of the testicle. 



The tunica albuginea is the fibrous coat which surrounds 

 the soft substance of the testis and is reflected at the posterior 

 border into its interior, forming a sort of septum, the cor]) us 

 Iliyhmori or mediastinum testis. This septum, wider above 

 than below, extends from the upper nearly to the lower end 

 of the gland, and sends off numerous trabeculse which join 

 the inner surface of the tunica albuginea. These divide the 

 organ incompletely into lobules. The tunica vasculosa (pia 

 mater testis) is a vascular plexus supported by areolar tissue 

 which covers the inner surface of the tunica albuginea and its 

 trabeculse. 



The gland substance consists of seminiferous tubules, which 

 are contained within the lobules above mentioned, each lobule 

 containing two or three seminiferous tubules. Each of these 

 latter is lined by several layers of epithelial cells, from which, 

 by a process of division (karyokinesis), are finally developed 

 the spermatozoa. 



The lobules are conical, their bases being turned toward 

 the circumference, their apices toward the mediastinum. In 

 the latter situation the tubules become straighter, and unite 

 to form twenty to thirty large ducts, the tubuli recti. These 

 tubuli recti open into a vascular network, the rete testis, which 

 lies in the substance of the mediastinum, and from this issue 

 twelve to twenty vasa efferentia, which pierce the tunica 

 albuginea and enter the globus major of the epididymis, where 

 they now become tortuous and form conical masses, the coni 

 vasculosi. 



The vas deferens, the continuation of the epididymis, is 

 the excretory duct of the testicle. From the globus minor 

 it runs along the inner side of the epididymis and back of the 

 testis, and in the spermatic cord to the internal ring; here 



