ca. LVIIL] 



THE TESTIS 



817 



scrotum before the testis and subsequently gets entirely cut off 

 from the remainder of the peritoneum. There are, however, many 

 animals in which the testes remain permanently in the abdomen. 

 The external covering of the testicle itself is a strong fibrous capsule, 

 called, on account of its white appearance, the tunica albuginea. 

 Passing from its inner surface*are a number of septa or trabeculse, 

 which divide the organ imperfectly into lobules. On the posterior 

 aspect of the organ the capsule is gioatly thickened, and forms a mass 

 of fibrous tissue called the 

 Corpus Highmorianum (body 

 of Highmore) or mediastinum 

 testis. Attached to this is a 

 much convoluted tube, which 

 forms a mass called the epi- 

 didymis. This receives the 

 ducts of the testis, and is 

 prolonged into a thick walled 

 tube, the vas deferens, by 

 which the semen passes to 

 the urethra. 



Each lobule of the testicle 

 contains several convoluted 

 tubes. Every tube commences 

 near the tunica albuginea, and 

 terminates after joining with 

 others in a straight tubule, 

 which passes into the body 



pf Highmore, Where it ends FlG . 60 6._Dissection of the base of the bladder and pro- 

 ill a network of tubes, the rete 

 testis. From the rete about 

 fifteen efferent ducts (vasa 

 efferentia) arise, which become 

 convoluted to form the coni 

 vasculosi, and then pass into 

 the tube of the epididymis. 



The convoluted or semi- 

 niferous tubes (fig. 607) have the following structure : each consists 

 of (1) an outer boundary of flattened connective tissue cells inter- 

 mingled with elastic fibres; (2) a fine membrana propria; (3) a 

 lining epithelium of many layers of germinal cells. Next the 

 membrana propria is a layer of cells, some of which are prim- 

 ordial germinal cells, others are spermatof/onia produced from the 

 primordial germinal cells, but differing from them in structure, and 

 the remainder are supporting or nurse cells which provide nutri- 

 ment for the developing spermatozoa. More internally, between the 



3? 



state gland, showing the vesiculae seminales and 

 vasa deferentia. a, Lower surface of the bladder at 

 the place of reflexion of the peritoneum ; 6, the part 

 above covered by the peritoneum ; i, left vas deferens, 

 ending in e, the ejaculatory duct; the vas deferens 

 has been divided near i, and all except the vesical 

 portion has been taken away ; s, left vesicula semi- 

 nalis joining the same duct ; s s, the right vas de- 

 ferens and right vesicula seminalis, which has been 

 unravelled ; p, under side of the prostate gland ; 

 m, part of the urethra ; u u, the ureters (cut short), 

 the right one turned aside. (Haller.) 



