TESTICLE. 



S49 



attached to the outer surface of the subjacent tunic — the tunica 

 alhuginea, dura mater testis, or proper tunic, which is a dense 

 fibrous membrane of a bluish -white colour. The tunica alhu- 

 ginea, after surrounding the testicle, is reflected into its substance, 

 forming a septum called the "mediastinum testis, or corputi 

 Highmorianum, from which originate numerous fibrous cords, 

 the traheculce septulce, which terminate on the inner surface of 

 the tunic, dividing the organ into lobules. Finally, we have the 

 most internal covering, the tunica vasculosa, or pia mater testis, 

 which is the vascular coat ; it lies beneath 

 the preceding one, enclosing the testicle, 

 and supporting the vessels, whose branches 

 ramify on the mediastinum testis andtrabe- 

 culae septulse. 



The testicle consists of a soft glandular 

 substance of a reddish-yellow colour, and is 

 divided into small distinct lohules, varying 

 in number from 200 to 300; they are coni- 

 cal in shape, having their base towards the 

 surface, and consist of several minute con- 

 voluted tubes, the tuhuli seminiferi, which 

 originate as loops or free cascal ends, and 

 are most convuluted at the base of the lobule, 

 gradually straightening as they approach 

 the apex at the mediastinum, where they 

 iJnite to form larger tubes, the vasa recta, 

 which enter the mediastinum and terminate 

 in a close network of tubules, the rete testis. 

 These pass upwards to the superior extremity 

 of the mediastinum, where they terminate 

 in the vasa efferentia, a number of small 

 ducts which perforate the tunica alhuginea; 

 straight at first, they shortly become con- 

 voluted, and form a series of conical masses, 

 the coni vasculosi, from whose bases larger tubes issue, the whole 

 forming the origin of the epididymis. 



Fig. 125.* 



Diagratnatic view of the 

 structure of the testis. 1 1. 

 Tunica alhuginea; 22, Medi- 

 astinum testis ; 3 3, Convol- 

 uted origins of seminiferous 

 tubes ; 4 4, Vasa recLa ; 5, 

 Kete testis ; 6, Vasa efifer- 

 entia; 7, Coni vasculosi 

 forming the globus major : 

 8, Body of epididymis ; 9, 

 Globus minor ; 10, Vas 

 deferens ; 11, Vasculum 

 aberrans. 



♦ [Fig. 125 represents the structure of the human organ. The chief differ- 

 ence to bear in mind is that of position, the long axis being nearly horizontal 

 in the horse, and the superior extremity in the cut is placed anteriorly in 

 that animal. — Ed.] 



