MORPHOLOGY OF THE HUMAN URINOGENITAL TRACT. 339 



3. The formation of the female and male urethra, and the 

 changes in the urethral orifice. 



1. The formation of the prepiitium clitoridis. — In the early- 

 stages, prior to the 3rd month, the genital eminence is covered 

 by an unbroken layer of epidermis, and sections show no attempt 

 at preputial formation. If, however, sections be examined 

 between the 3rd and 5th months, a remarkable condition is 

 found. In sagittal mesial section (fig. 20) one sees the glans 

 formed and bounded by cells continuous with the deep layer of 

 the epidermis. The preputial aperture has formed, but is filled 

 with a solid plug of cells, while between the glans surface and 

 the inner surface of the prepuce we have also a solid layer. 

 This is often represented, but most erroneously, as a fusion of 

 the epithelial surfaces of the glans and prepuce. In coronal 

 section one sees a remarkable horse-shoe arrangement, the out- 

 line of the horse-shoe being mapped out by deeply-stained cells, 

 whilst between these we have less deeply stained cells. In 

 certain lateral sections, again, we get an analogous arrange- 

 ment, but a circular one. 



These appearances shew that the prepuce is developed as 

 follows : — At the apex of the glans the epidermis passes in, 

 following the glans outline.^ The active epidermic cells, more 

 deeply stained, rest on the glans and the inner preputial sur- 

 face ; between these lie the less deeply-stained cells correspond- 

 ing to the more superficial cells of the epidermis. We see here, 

 then, very well illustrated, how the epidermis forms lumina. 

 In the epidermis at this stage we have an active deep layer, 

 and above it the less active cells with a tendency to desquamate. 

 When the epidermis has passed in as described, the central cells 

 in the horse-shoe arrangement, for instance, desquamate, and 

 we then get the movable prepuce in the child. The prepuce is 

 thus formed by the epidermis parsing in round the glacis, with its 

 active cells deep, its less active and desquamating ones central ; the 

 desquamation of the latter makes the mobile prepuce. 



It is usually said that the prepuce grows forwards from the 

 glans root, that the inner surface adheres to the glans and then 



^ I have sections to show that the glans is formed first in the male, at any 

 rate. 



