KLOJ'MK.VJ 



-JHK J'KH'OJ/.VHVE ORGANS, 



.... - 



th'- ^'-rminal ridge by the underlying mesoMastic stroma, whereby the epithelial 

 mats becomes broken up nders and cords that extend into the subjacent 



stroma. '1 h< " 1) ' ords are composed of two kinds of elements, the numerous chief 

 'p"'-' J the larger sperm-cells, the direct descendants of the indifier- 



<-nt primary germ-cells, winch they embrace. About the fifth week a layer of 

 ..'i nates itself between the superficial and deeper portions of the epi- 

 thelial ma--/., :; a peripheral zone. This ingrowth results in the 

 formation of a robust fibrous envelope, the tunica albuginea, around the entire tffttt, 

 while the separated mesothelial layer differentiates into the serous covering. The 

 c<-ll-cords Income subdivided by the ingrowth of the mesoMastk stroma into mnirr 

 spheri- al masses, which subsequently are converted into the seminiferous MMifrtu 

 while- from the stroma are supplied the interlobular septa and the intralobular support- 

 ing tissue. About the sixth week additional cell-cords grow into the young testis 

 from the adjacent Wolfnan tubules. These 



ingrowths invade the attached border of FIG. 17181. 



the and become the medullary 



cords, which are -ed that each 



comes into relation with one of the spheri- 

 cal epithelial cell-masses. Although both 

 the latter and the medullary cords are 

 solid, the later relation of the secreting 

 tubules of the gland to the excretory 

 channels is thus foreshadowed, since from 

 the ingrowths from the Wolfnan tubules 

 are derived the straight tubules anc - 

 of the r< The farther differen- 



tiation of the seminiferous canals, which, 

 as well as the medullary cords, are with- 

 out lumen until near puberty, proceeds 

 from the growth and branching of the cell- 

 masses, the cells of which become the epi- 

 thelium of the tubules. The latter are 

 enclosed by an investment of condensed 

 mesoblastic stroma continuous with the 

 supporting tissue and framework of the 

 gland. At the approach of sexual ma- 

 turity the primary sperm-cells within the 

 tubules proliferate and become the sperma- 

 togonia, while from other epithelial ele- 

 ments are derived the Sertoli cells. The 

 roles played by these elements in the pro- 

 duction of the spermatozoa are described 

 under Spermatogenesis (page i 



Coincidently with the growth of the 

 testis the Wolffian body atrophies, with the exception of some of its tubules and duct, 

 which increase and, in conjunction with the medullary cords also derived from the 

 mesonephros, establish the elaborate excretory- passages of the sexual gland. From 

 the Wolffian tubules are developed the coni vasculosi and the ductuli efierentes, while 

 the Wolrhan duct gives rise to the tube of the epididymis. the vas deferens, and, as 

 a secondary outgrowth, the seminal vesicle. The caudal group of mesonephric tubules 

 are represented in both sexes by rudimentary structures, which in the male are the 

 paradidymis and the vasa aberrantia. The appendix of the epididymis, or stalked 

 hydatid, probably also owes its origin to the Wolffian duct. 



Although, as is evident from the foregoing, the Wolfnan tubules and duct are 

 largely concerned in the development of the generative tract in the male, the 

 lerian duct is not without representation, since its two extremities persist. The 

 upper (after migration lower) end remains as the appendix of the testis, and the 

 lower, fused with its fellow, is seen as the prostatic utricle, which, therefore, - 

 homologue of the vagina and, possibly, the uterus. In exceptional cases, where it 



Globus minor 



Longitudinal 



