THE UKO-GENITAL SYSTEM. 



117 



anterior layer of the triangular ligament. The female urethra 

 corresponds to the prostatic part of the male urethra above the 

 opening of the sinus pocularis (Figs. 92 and 93). 



The Hymen is formed at the junction of the vagina with the 

 uro-genital sinus. The terminal parts of the Miillerian ducts, 

 which form the vagina, are at first solid epithelial cords, the 

 epithelial mass being derived from the bulbous terminations of the 

 Wolffian ducts (Berry Hart). After the Miillerian ducts fuse to form 

 the vagina they become hollowed out, all but the terminal piece, 

 which forms the hymen and it, as a rule, is perforated (Fig. 94). 



os. externum 

 rectum 



uagina 



perineal body 



clitoris hymen. 



Fig. 94.— A section to show the condition of the Vagina and Uterus at the 7th month 

 of foetal life. 



Cases occur in which the hymen is a complete or even thick 

 septum, or occasionally the whole vagina may retain the foetal ■ 

 solid form (atresia vaginae). 



The Vagina is at first not only solid, but extremely short ; the 

 downgrowth of the vesico-vaginal septum adds greatly to its 

 length (Fig. 92 A and B). It is separated off from the uterine 

 segment of the Miillerian duct in the fifth month (Fig. 92 B) by 

 (1) the growth of the external os and formation of the labia; (2) 

 by its epithelium becoming stratified, while that of the uterus and 

 upper half of the cervix remains columnar. 



The Uterus is formed by the fusion of the Miillerian ducts ; its 

 muscular walls and thickened mucous lining appear in the 5 th 



