690 



MANUAL OF PHYSIOLOGY. 



duct, which has acquired a glandular structure, is the Wolffian 

 body or primitive kidney of the embryo, whilst the Wolffian duct 

 corresponds to the primitive ureter. 



The epithelium lining the interval between the somatopleure 

 and splanchnopleure (pleuro-peritoneal cavity), close to their 

 origin from the uncleft mesoblast, becomes columnar in character. 



FIG. 277. 



Section of the inner part of the pleuro-peritoneal cavity through the 

 origin of the genito-urinary organs. (Waldeyer.) L. Somatopleure. m. 

 Splanchnopleure a. Germinal epithelium. C, o. Primitive ova. E. Meso- 

 blast forming the ovary. WK. Wolffian body. y. Wolffian duct. a'. Epi- 

 thelium giving rise to the duct of Miiller z. 



It receives the name of the germinal epithelium. An involution 

 of this takes place into the mesoblast, just below the somato- 

 pleure, and becomes shut off, and forms a hollow cylinder. 



By this means a second duct is formed in close relation to the 



