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HANDBOOK OF PHYSIOLOGY. 



lumnar ciliated epithelium (fig. 447), is commonly described as con- 

 sisting (fig. 447) of & globus minor (#), the body (e), and the globus major 

 (I.) When unravelled it is found to be constructed of a single tube, meas- 

 uring about twenty feet in length. 



At the globus major this duct divides into ten or twelve small 

 branches, the convolutions of which form coniform masses, named Coni 

 vasculosi; and the ducts continued from these, the Vasa efferentia, after 

 anastomosing, one with another in what is called the Rete testis, lead 

 finally as the Tubuli rection: Vasa recta to the seminal tubules (tubuli 

 seniiniferi), which form the proper substance of the testicle. The 

 epithelium lining the coni vasculosi and vasa elferentia is columnar and 

 ciliated ; that of the rete testis is squamous. 



The seminal tubules are arranged in lobules, separated from one 

 another by incomplete fibrous septa or cords, which pass from the front 

 of the tunica albuginea internally to a firm incomplete vertical septum 

 of thick extending fibrous tissue at the posterior border, from the upper 

 to near the lower part, called the corpus Higlmwri, or mediastinum 

 testis. Through this very firm fibrous tissue pass the seminal tubes from 

 the vasa recta. The tunica albuginea is covered by a very fine plexus of 

 blood-vessels internally, derived from the spermatic vessels. The fibrous 

 cords which may contain unstriped muscle are also covered with a similar 

 capillary plexus. 



Tubuli Seminiferi. The seminal tubes, which compose the paren- 

 chyma of the testicle, are loosely arranged in lobules between the connec- 

 tive tissue septa. 



They are relatively large, very wavy, and much convoluted; and 

 they possess a few lateral branches, by which they become connected 



Fig. 449. From a section of che testis of dog, showing portions of seminal tubes. A, semi- 

 nal epithelial cells, and numerous small cells loosely arranged ; B, the small cells or sperm- 

 atoblasts converted into "spermatozoa; groups of these in a further stage of development. 

 (Klein.) 



into a network. They form terminal loops, and in the peripheral por- 

 tion of the testis the tubules are possessed of minute lateral caecal 

 branchlets. 



Each seminal tubule in the adult testis is limited by a membrana 



