402 



EMBRYOLOGY. 



converted into the male member, or the penis, which corresponds to 

 the clitoris of the female. Like the latter, it possesses an anterior 

 knoh-like enlargement, the glans {M gp), which is embraced by a 

 fold of the skin, the prseputium (M* vh). The sinus urogenitalis, 

 which in the female remains short and broad as the vestibulum 

 vaginse, is in the male converted by a process of fusion into a long 

 narrow canal, the urinary tube or urethra. This results from the 

 fact that the furrow on the under surface of the genital protuberance 

 {M gr) becomes elongated during the development of the latter and 

 at the same time deeper, and that the sexual folds {gf) bordering it 

 protrude farther, coming into immediate contact along their edges 

 {M*) as early as the fourth month, and begin to fuse together. 



The posterior end of the urethra early (second month) undergoes 

 changes by which the prostata (fig. 222 jar) is formed. The walls 

 become greatly thickened, acquire non-striate muscular tissue, and 

 constitute a ring-like ridge, into which evaginations from the epi- 

 thelium of the tube penetrate, and by their branchings furnish the 

 glandular portions of the organ. On its posterior wall are found, as 

 is well known, the openings (dej) of the vasa def erentia, and between 

 them the sinus prostaticus or uterus masculinus {urn), produced by 

 the fusion of the Miillerian ducts. 



The genital ridges (fig. 231 M gw), which in woman become 

 the labia majora, also undergo a fusion in man. They siu-round 

 the root of the penis and then fuse in the median plane, where 

 the place of union is indicated afterwards by the so-called raphe 

 scroti (M* r). Into the scrotum {M* hs) thus formed the testes, 

 toward the end of embryonic Hfe, migrate, as previously described. 



From the fact that originally the external sexual parts are con- 

 stituted exactly alike in both sexes, it is evident why, with a 

 derangement of the normal course of development, forms come into 

 existence in which it is sometimes extremely difficult to determine 

 whether one has to do with male or female external parts. These 

 are cases which in earlier times were erroneously designated as 

 hermaphroditism. There are two ways in which they may arise. 

 They are either to be referred to the fact that in a female the 

 process of development has proceeded further than normally (i.e., 

 as in the male), or that in a male the process of development has 

 suffered an early interruption, and thereby led to formations which 

 are similar to the female genital parts. 



As far as regards the first kind of malformations, the genital 

 eminence in the female occasionally assumes such a size and form 



