226 



THE UROGENITAL SYSTEM 



end of the glans, which becomes the glans penis. By the disappearance of the 

 central cells of the epithehal downgrowth an outer cyhndrical mantle, the pre- 



A B C 



Fig. 236. — Three stages in the development of the female external genitalia (after Toumeux in 

 Heisler). 1, Clitoris; 2, glans clitoridis; 3, urogenital aperture on each side of which are the labia 

 minora (7); 4, labia majora; 5, anus; 7, labia minora. 



pucium OX fore-skin, is formed about the spherical glans (cf. Fig. 158). Where 

 the epithelial downgrowth is incomplete the glans and fore-skin remain con- 

 nected, the persisting connection being the frenulum prepucii. 



W '■'■'If' 



A B c 



Fig. 237. — Three stages in the development of the male external genitals (after Toumeux in 

 Heisler). 1, Penis; 2, glans; 3, urogenital groove; 4, genital swellings corresponding to labia majora 

 of female; 5, anus; 7, scrotal area with perineo-scrotal raphe. 



The urogenital sinus, as we have seen, extends out into the phallus and in 

 the glans becomes the solid urethral plate. With the great elongation of the 

 male phallus, the open portion of the urogenital sinus also is lengthened and 



