DESCENT OF THE TESTES. 



267 



(seam) remains to indicate their place of fusion. A reduplication of the 

 lesser folds over the glans forms the prepuce. Outside of these folds there 

 are two larger elevations of skin, one on either side of the root of the penis. 

 They extend toward the anus, between which and the penis they fuse in 

 the median line forming a continuation of the raphe already mentioned. 

 These larger genital folds thus produce the scrotum. 



Descent of the testes. The peritoneal cavity sends a prolongation, 

 the processus vaginalis, over the pubic bone into each half of the scrotum. 

 The testis and epididymis at this stage lie behind the peritonaeum of the 

 abdominal cavity (Fig. 302, B). A large retroperitonaeal column of con- 

 nective tissue, the gubernaculum testis, extends from the posterior end of 

 each testis into the depth of the scrotum. For reasons still obscure, such 

 as unequal growth or the shortening of this cord, the testes pass down 

 in front of the pubic bones, into the scrotum (Fig. 302, C). The Wolffian 



FIG. 302. A, DIAGRAM OF THE EMBRYONIC EXTERNAL GENITAL ORGANS IN THE MALE; B, C, D, 

 DIAGRAMS OF THE DESCENT OF THE TESTIS. (After Eberth.) 



a., Anus; ep., epididymis; g., glans penis; g. f., lesser genital folds; g. g. f., greater genital folds; p. c. 

 peritonaeal cavity; p. v., processus vaginalis; r., raphe; t., testis; t. v., tunica vaginalis (p. 1., parie- 

 tal; v. 1., visceral layer); u. s., urogenital sinus. 



duct is bent over the ureter as shown in Fig. 301. Except on its dorsal 

 border the testis is closely invested by the peritonaeum of the processus 

 vaginalis. Later the distal part of the processus becomes separated from 

 the abdominal cavity by the obliteration of its stalk. The part remain- 

 ing about the testis is the tunica vaginalis, having a parietal and a visceral 

 layer as shown in Fig. 302, D. The descent of the testes is completed 

 shortly before birth and the obliteration of the stalk of the processus 

 follows. 



TESTIS. 



Sustentacul-ar and sexual cells. Among the cells of the cords which 

 develop in the genital ridges there are some which are larger than the rest, 

 and are further characterized by abundant clear protoplasm and large 

 round nuclei. Two of these sexual cells are shown in Fig. 303, from a 

 testis at birth. At this stage the lumen of the convoluted tubules is imper- 



