SEX-CORDS AND SPERMATOGONIA IN CHICK 377 



played any role in the histogenesis of the male sex gland. He 

 believed that the sex cords arose in the middle portion of the 

 Wolffian body and that they grew into the stroma under the 

 germinal epithelium. The primordial germ-cells degenerated 

 and the definitive sex elements arose from the Wolffian tissue. 



Braun (77), like Waldeyer (70) and Bornhaupt ('67), de- 

 scribed two kinds of cells in the germinal epithelium, the cylin- 

 drical, differentiated, peritoneal or coelomic cells and the large 

 primordial germ-cells. Braun found in reptiles (Lacerta) that 

 the walls of the Wolffian tubules produced cell buds, which grew 

 in height, anastomosed one with the other, and ended by send- 

 ing up cord-like, cellular processes which fused with the germinal 

 epithelium. He called these processes segmental cords, and 

 believed that they gave rise to the seminiferous tubules of the 

 testis. 



In reality, Braun did not describe the origin of the true sexual 

 cords, but rete cords, or cords of uro-genital union. Up to the 

 time of Mihalkowics ('85) the true sex cords were constantly 

 confused, both as to origin and function with the rete cords. 

 The rete cords, or cords of uro-genital union, arise prior to the 

 sex cords in the male and female. The rete cords, according to 

 Mihalkowics ('85) and Sainmont ('05), are derived from the Wolff- 

 ian tubules and the epithelium of Bo^\Tiian's capsule. Accord- 

 ing to Allen ('04, '05 and '06), they appear in reptiles and mam- 

 mals as ingrowths of the germinal epithelium. Bouin ('00), in 

 the frog, Firket ('14), and Swift ('15), in the chick, beheved them 

 to arise as condensations of the mesenchyme between the ger- 

 minal epithelium and the Wolffian body. Whatever their ori- 

 gin they do not produce the definitive sex-cells, but are devel- 

 oped into the tubuli recti and rete testis; interposed between the 

 tubuli contorti, which are of true sex cord origin, which pro- 

 duce the definitive sex-cells, and the vasa efferentia, which are 

 modified Wolffian tubules. 



Mihalkowics ('85) described the origin of the true sex cords 

 from the germinal epithelium and replaced Braun's name seg- 

 mental cord with sex cord. He did not get the details exactly 

 correct — that was left for Janosik — but his idea was correct. 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 20, NO. 3 



