THE EXCRETORY AND REPRODUCTIVE SYSTEMS. 



181 



lique muscle, and of the tunica 'vaginalis. On the testis 

 between these two coats is a 

 thin layer of fibers forming 

 the levator scroti muscle. 

 The tunica vaginalis is com- 

 posed of three layers, the 

 outer of which is the fascia 

 propria, derived from the 

 transversalis fascia. The 

 other two are derived from 

 the peritoneum. 



During fetal life the testes 

 lie in the abdominal cavity, 

 and when they descend into 

 the scrotum about the time 

 of birth, a double layer of 

 peritoneum is pushed down 

 before them through the in- 

 guinal canal, forming a di- 

 verticulum whose blind end 

 lies within the scrotum, 

 while the constricted por- 

 tion forms a channel for 

 the vas deferens, spermatic 

 nerve, and vessels. These 

 three structures form the 

 spermatic cord (Fig. 51). 

 The fascia propria (tunica 

 vaginalis communis) is in- 

 separably united with the 

 adjacent parietal layer of 

 the peritoneum. The vis- 

 ceral layer of peritoneum is 

 quite delicate and trans- 



FIG. 87. VENTRAL ASPECT OF THE 

 MALE REPRODUCTIVE ORGANS. 



cr, One of the crura of the penis ; 

 ep, epididymis revealed by cut- 

 ting and reflecting vg, a piece of 

 the tunica vaginalis and albu- 

 ginea; et, external abdominal 

 ring; it, internal abdominal ring; 

 in, inguinal canal ; g, glans penis ; 

 gd, Cowper's glands; pe, penis; 

 pr, prostate gland; re, rectum; 

 /, testis from which the tough 

 sheath composed of the levator 

 scroti muscle and cremaster fascia 

 has been removed, leaving it en- 

 veloped by the tunica vaginalis; 

 is, testicle from which a portion 

 of the tunica vaginalis has been 

 reflected; nth, urethra; ur, ure- 

 ters ; vd, spermatic cord ; vdd, vas 

 deferens within the abdominal 

 cavity; vg, tunica vaginalis re- 

 flected; i'g 2 , tunica vaginalis; v, 

 spermatic vein. 



