TIG 



HANDBOOK OF PHYSIOLOGY. 



nalis or serous covering of the organ ; the communication between the 

 tunica vaginalis and the cavity of the peritoneum being closed only a 

 short time before birth. In its descent, the testicle or ovary of course 

 retains the blood-vessels, nerves, and lymphatics, which were supplied 

 to it while in the lumbar region, and which are compelled to accompany 

 it, so to speak, as it assumes a lower position in the body. Hence the 

 explanation of the otherwise strange fact of the origin of these parts at 

 so considerable a distance from the organ to which they are distributed. 

 Descent of the Testicles into the Scrotum. The means by which the 

 descent of the testicles into the scrotum is effected are not fully and ex- 

 actly known. It was formerly believed that a membranous and partly- 



FIG. 498. Diagram of the Wolfflan bodies, Mullerian ducts and adjacent parts previous to 

 sexual distinction, as seen from before, sr, the suprarenal bodies; r, the kidneys; ot, common 

 blastema of ovaries or testicles; W, Wolfflan bodies; w, Wolfflan ducts; m, m, Mullerian ducts; g, 

 genital cord; ug, sinus urogenitalis; i, intestine; cZ, cloaca. (Allen Thomson.) 



muscular cord, called the gubernaculum testis, which extends while the 

 testicle is yet high in the abdomen, from its lower part, through the ab- 

 dominal wall (in the situation of the inguinal canal) to the front of the 

 pubes and lower part of the scrotum, was the agent by the contraction 

 of which the descent was effected. It is now generally thought, how- 

 ever, that such is not the case ; and that the descent of the testicle and 

 ovary is rather the result of a general process of development in these 

 and neighboring parts, the tendency of which is to produce this change 

 in the relative position of these organs. In other words, the descent is 



