242 ABDOMEN 



of Kolliker. Now free the tail and body of the epididymis from 

 the back of the gland by cutting the serous covering as it passes 

 from one to the other, and breaking through the fibrous tissue 

 which intervenes between the tail and the lower part of the testis. 

 Do not interfere with the head of the epididymis. When the 

 body and tail of the epididymis are turned aside, the testis should 

 be divided transversely, with a sharp knife, about its middle, 

 into an upper and a lower portion. 



Structure of the Testis. The cut surface of the lower 

 part of the testis should now be studied. The dense, tough 

 fibrous coat which envelops it, under cover of the visceral layer 

 of the tunica vaginalis, is the tunica albuginea. 



At the posterior border of the testis the tunica albuginea 

 forms a thickened ridge, called the mediastinum testis, which 

 projects forwards into the interior of the testis. 



The mediastinum testis extends along the whole length 

 of the posterior border of the gland. It is traversed by the 

 arteries, veins, and lymph vessels of the testis, and, in 

 addition, it is tunnelled by a plexus of intercommunicating 

 seminal channels which form, collectively, the rete testis. 



From the front and sides of the mediastinum testis radiat- 

 ing fibrous strands pass through the substance of the testis. 

 They are the cut margins of incomplete fibrous septula which 

 extend towards the deep surface of other parts of the tunica 

 albuginea and become connected with them (Figs. 105, 107). 

 By means of the partitions, the space enclosed by the tunica 

 albuginea becomes broken up into a large number of partially 

 separated lobules or compartments, two to three hundred in 

 number. The fibrous framework of the testis consists therefore 

 of the tunica albuginea with the mediastinum testis and 

 the septula. 



The blood-vessels have a very definite arrangement with 

 reference to fibrous framework. After they have passed 

 through the mediastinum they spread out upon the surfaces 

 of the fibrous septula and on the deep surface of the tunica 

 albuginea. The vascular mesh-work thus formed is sometimes 

 called the tunica vasculosa. 



The proper glandular substance of the testis is lodged 

 within the compartments described above. It consists of four 

 to six hundred fine hair-like tubes, termed the contorted semini- 

 ferous tubules, each of which is about 60 cm. (two feet) long. 

 Two or more occupy each compartment, and constitute what 

 is called a testicular lobule. In ea'ch testicular lobule the 



