DEVELOPMENT OF THE WOLFFIAN BODIES, ETC. 787 



Fiir. 295. 



INTERNAL ORGANS OF (JKNEBA- 

 TION in a foetal pi nearly 10 centimetres 

 long. From a specimen in the author's 

 possession. 1, 1. Kidneys. 2, 2. Wolffian 

 bodies. 3, 3. Testicles. 4. Urinary blad- 

 der. 6. Intestine. 



tains muscular fibres, which may be easily detected, in the human foetus, 



during the latter half of intra-uterine 



life. At the period of birth, however, 



or soon afterward, they have usually 



disappeared. 



That portion of the excretory tube 

 of the testicle which is situated out- 

 side the crossing of the gubernaculum, 

 is destined to become afterward con- 

 voluted, and converted into the epi- 

 didymis, That which is situated 

 inside the same point remains com- 

 paratively straight, but becomes con- 

 siderably elongated, and is finally 

 known as the vas deferens. 



As the testicles descend still far- 

 ther in the abdomen, they continue to 

 grow, while the Wolffian bodies, on 

 the contrary, become smaller ; and at 

 last, when the testicles have arrived at the internal inguinal ring, the 

 Wolffian bodies have altogether disappeared, or have become so altered 

 that they are no longer recognizable. In the human foetus, the testicles 

 reach the internal inguinal ring about the termination of the sixth 

 month (Wilson). 



During the succeeding month, a protrusion of the peritoneum takes 

 place through the inguinal canal, in advance of the testicle; the last- 

 named organ still continuing its descent. As it passes into the scrotum, 

 loops of muscular fibres are given off from the lower border of the in- 

 ternal oblique muscle of the abdomen, extending downward with the 

 testicle, upon it and upon the elongating spermatic cord. These con- 

 stitute afterward the cremaster muscle. 



At last, the testicles descend quite to the bottom of the scrotum. 

 The convoluted portion of the efferent duct, namely, the epididymis, 

 remains attached to the body of the testicle ; while the vas deferens 

 passes upward, in a reverse direction, enters the abdomen through the 

 inguinal canal, again bends downward, and joins its fellow of the oppo- 

 site side ; after which they both open into the prostatic portion of the 

 urethra by distinct orifices, situated on either side of the median line. 

 At the same time, two diverticula arise from the median portion of the 

 vasa deferentia, and, elongating in a backward direction, beneath the 

 base of the bladder, become developed into sacculated reservoirs, the 

 vesiculse seminales. 



The left testicle is a littler later in its descent than the right ; but it 

 afterward passes farther into the scrotum, and, in the adult condition, 

 usually hangs a little lower than the corresponding organ on the oppo- 

 site side. 



After the testicle has passed into the scrotum, the serous pouch, 



