1210 



SPLANCHNOLOGY 





the fact that their cytoplasm has no affinity for ordinary stains, but assumes a brownish tinge 

 when treated by osmic acid. The path along which they travel into the embryo is a very definite 

 one, viz., "from the yolk sac upward between the splanchnopleure and gut in the hinder portion 

 of the embryo." This pathway, named by Beard the germinal path, "leads them directly to the 

 position which they ought finally to take up in the 'germinal ridge' or nidus." A considerable 

 number apparently never reach their proper destination, since "vagrant germ cells are found in 

 all sorts of places, but more particularly on the mesentery." Some of these may possibly find 

 their way into the germinal ridge; some probably undergo atrophy, while others may persist 

 and become the seat of dermoid tumors. 



Genital cord 



Blood-vessel - 

 Ovarian follicle - 



Germinal 

 epithelium 



Primitive ova 

 ~ Cell-nest 



Tunica 

 albuginea 



..Interstitial 

 cell 



FIG. 1113. Section of the ovary of a newly born child. (Waldeyer.) 



The Testis. The testis is developed in much the same way as the ovary. Like 

 the ovary, in its earliest stages it consists of a central mass of epithelium covered 

 by a surface epithelium. In the central mass a series of cords appear (Fig. 1114), 



and the periphery of the mass is con- 



Epithelium n^y JU _^, tt , + *~\ verted into the tunica albuginea, thus 



excluding the surface epithelium from 

 any part in the formation of the 

 tissue of the testis. The cords of 

 the central mass run together toward 

 the future hilus and form a network 

 which ultimately becomes the rete 

 testis. From the cords the seminifer- 

 ous tubules are developed, and be- 

 tween them connective-tissue septa 

 extend. The seminiferous tubules 

 become connected with outgrowths 

 from the Wolffian body, which, as 

 before mentioned, form the efferent 

 ducts of the testis. 



Descent of the Testes. The testes, 

 at an early period of fetal life, are 

 placed at the back part of the ab- 

 dominal cavity, behind the perito- 

 neum, and each is attached by a 

 peritoneal fold, the mesorchium, to the mesonephros. From the front of the meso- 

 nephros a fold of peritoneum termed the inguinal fold grows forward to meet and 

 fuse with a peritoneal fold, the inguinal crest, which grows backward from the 



Supporting \ 

 cell 



Genital 

 cell 



FIG. 



1114. Section of a genital cord of the testis of a human 

 embryo 3.5 cm. long. (Felix and Biihler.) 



