400 



THE DEVELOPMENT OF THE CHICK 



old. The germinal epithelium covers the surface and is continu- 

 ous with the ovigerous strands projecting far into the stroma. 

 The strands are broken up in the stroma into nests of cells; 

 next the germinal epithelium are found characteristic primi- 

 tive ova, but in deeper situations the primitive ova are larger 

 and each is accompanied by a group of epithelial cells, which are 

 distinctly differentiated as granulosa cells of young follicles in 





Fig. 230. — Cross-section of the ovary of a fledgling of Numenius ar- 

 cuatus 3-4 days old. The germinal epithelium is below. (After 

 Hoffmann.) 

 s. c, Sexual cords. 



the deepest. Thus the young follicles arise by separation of 

 nests of cells from the ovigerous strands within the stroma; 

 each nest includes a young ovocyte and a group of epithelial 

 cells which arrange themselves in a single layer of cuboidal cells 

 around the ovocyte. On each side of the free border of the ovary 

 the embryonic state persists, and it is not known whether this 



