THE URINOGENITAL SYSTEM 



397 



sexual and a posterior non-sexual portion. In the latter part of 

 the period of incubation the non-sexual portion undergoes absorp- 

 tion while the anterior portion becomes converted into the epididy- 

 mis. 



The increase of primitive ova in the germinal epithelium and 

 their migration into the sexual cords continues until about the four- 

 teenth day. In the meantime the stroma has increased notably 

 in amount; it constitutes a considerable layer between the cords, 



:fe"*ir 



FIG. 228. Cross-section through the periphery of the testis of a 

 just hatched chick. (After Semon.) The sexual cords have 

 acquired a lumen, and the walls of the canals are formed of the 

 primitive ova and the cells of the sexual cords, or supporting 

 cells. The connective tissue forms septulse, connecting with the 

 albuginea ; the remains of the germinal epithelium form the serous 

 covering of the testis. 

 Alb., Albuginea. c. T., Connective tissue of the septulae testis. 



1., Lumen of the sexual cords, pr. O., Primitive ova. s. C., Sexual 



cord. 



and begins now to form a layer between the germinal epithelium 

 and the distal ends of the sexual cords. This layer forms the 

 albuginea of the testis, and with its establishment the production 

 of the primitive ova from the germinal epithelium ceases, and the 

 latter becomes reduced to an endothelial layer (Fig. 228). 



