VI.] 



THE GERMINAL EPITHELIUM. 



165 



The median portion of the ridge is occupied by the 

 projection of the Wolffian body, and here the epithelium 

 rapidly becomes flattened. 



On the inside of the ridge, however, that is on the side 

 looking towards the splanchnopleure, the epithelium not only 

 retains its columnar character, but grows several cells deep 

 (Fig. 51, a), while at the same time the mesoblast (E) under- 

 lying it becomes thickened. In this way, owing partly to 

 the iu creasing thickness of the epithelium, and partly to 

 the accumulation of mesoblast beneath it, a slight eminence 

 is formed, which when viewed from above, after opening the 



Fig. si. 



aw — — 



Section of the intermediate Cell-mass on the Fourth Day. (From 



Waldeyer.) Magnified 160 times. 



m. mesentery. L. somatopleure. a', portion of the germinal epithelium from 

 which the involution to form the duct of Muller (z) takes place, a. thickened 

 portion of the germinal epithelium in which the primitive ova C and o are 

 lying. E. modified mesoblast which will form the stroma of the ovary. 

 WK. "Wolffian body. y. Wolffian duct. 



