786 



GENERATION. 



perior and thickest portion, is pierced by a number of openings, and lodges 

 blood-vessels and seminiferous tubes. From the mediastinum, delicate, radi- 

 ating processes of connective tissue pass to the inner surface of the tunica 

 albuginea, dividing the substance of the testicle into imperfect lobules, which 

 lodge the seminiferous tubes. The number of these lobules has been esti- 

 mated at one hundred and fifty to two hundred. Their shape is pyramidal, 

 the larger extremities presenting toward the surface, with the pointed ex- 

 tremities situated at the mediastinum. 



Lining the tunica albuginea and following the mediastinum and the 

 processes which penetrate the testicle, is a tunic, composed of blood-ves- 

 sels and delicate, connective tissue, called the tunica vasculosa, or pia mater 

 testis. 



Lodged in the cavities formed by the trabeculae of connective tissue, are 

 the seminiferous tubes, in which the male elements of generation are devel- 

 oped. These tubes exist to the number of about eight hundred and forty in 



each testicle and constitute almost 

 the entire substance of the lobules. 

 The larger lobules contain five or six 

 tubes, the lobules of median size, 

 three or four, and the smallest en- 

 close sometimes but a single tube. 

 Each tube presents a convoluted 

 mass, which can be disentangled un- 

 der water, particularly if the testicle 

 be macerated for several months in 

 water with a little nitric acid. The 

 entire length of the tube when thus 

 unravelled is about thirty inches (7*6 

 decimetres), and its diameter is -g-J-g- 

 to ^ of an inch (125 to 166 ^). It 

 begins by two to seven short, blind 

 extremities and sometimes by anas- 

 tomosing loops. The caecal diverti- 

 cula are usually found in the exter- 

 nal half of the tube, and their length 

 is -^ to ^ of an inch (2*1 to 3*2 mm.). 



FIG. 286. Testicle and epididymis of the human sub- The anastomoses ai'6 Sometimes be- 

 ject (Arnold). , _ ,., , , , , 



a, testicle; 6, 6, 6, &, lobules of the testicle ; c, c, vasa een the tubes of different lobules, 

 /f/,/,' cones of e tne Jiobus ma jor^the epididy- sometimes between tubes in the same 



mis ; gr, gr, epididymis ; 7i, 7i, vas deferens ; t, vas l/~v nil lrk nrirl rmpfitrp<3 Vipfwppn rlif 



aberrans ; m, m, branches of the spermatic ar- AODUie ana Sometimes Derwee 



tery, to the testicle and epididymis ; n,n,n, ram- f pv pnf rninf in tVip amp tnhp As 



incltion of the artery upon the testicle : o, def- l P J D6 ' AS 



the tubes pass toward the posterior 

 portion of the testicle, they unite into 

 about twenty straight canals, called the vasa recta, about -fa of an inch (0-33 

 mm.) in diameter, which penetrate the mediastinum testis. In the mediasti- 

 num the tubes form a close net- work, called the rete testis ; and at the upper 



