THE URINOGENITAL SYSTEM 405 



tinues up to about the one hundredth hour or a Httle later, and 

 a second stage in the development of the cortical cords then 

 begins: The cords grow rapidly and fill the space on the medio- 

 dorsal aspect of the Wolffian body, and then come secondarily 

 into relation with the renal corpuscles of the latter and the sexual 

 cords. 



According to Semon and Hoffmann the relation thus estab- 

 lished is a primary one, that is to say, that the cortical cords 

 arise from the same outgrowths of the capsules of the renal cor- 

 puscles that furnish the sexual cords. Rabl agrees essentially 

 with Soulie, and it seems probable that Semon and Hoffmann 

 have overlooked the first stages in the origin of the cortical cords 

 of the suprarenal corpuscles. 



During the fifth, sixth, and seventh days there is a very 

 rapid increase of the cortical cords accompanied by a definite 

 circumscription of the organ from the surrounding mesenchyme; 

 however, no capsule is formed yet. The topography of the organ 

 on the eighth day is shown in Figs. 150 and 182. Whereas during 

 the fourth, fifth, and sixth days the arrangement of the cortical 

 cells is in masses rather than in cords, on the eighth day the 

 cords are well developed, in form cylindrical with radiating cells, 

 but no central lumen. The organ has become vascular, and the 

 vessels have the form of sinusoids, i.e., they are moulded on the 

 surface of the cords with no intervening mesenchyme. 



Origin of the Medullary Cords. The medullary cords take 

 their origin unquestionably from cells of the sympathetic ner- 

 vous system. During the growth of the latter towards the mesen- 

 tery, groups of sympathetic cells are early estabUshed on or near 

 the dorso-median surface of the cortical cords (Fig. 226). The 

 ingrowth of the sympathetic medullary cords does not, however, 

 begin until about the eighth day. At this time there is a large 

 sympathetic ganglionic mass on the dorso-median surface of the 

 anterior end of the suprarenal, and strands of cells characterized 

 sharply by their large vesicular nuclei and granular contents 

 can be traced from the ganglion into the superficial part of the 

 suprarenal. These cells are precisely like the specific cells of 

 the ganglion, perhaps a little smaller, and without axones. On 

 the eleventh day these strands have penetrated through a full 

 third of the thickness of the suprarenal, and are still sharply 

 characterized, on the one hand by their resemblance to the 



