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Fred. J. Taussig 



wall. Directl}- anterior to this fold is the true h}'ineii, a memhrane two 

 to three millimeters in height and about one-half to one millimeter in 

 thickness, likewise springing mainly from the dorsal wall (Figs. 4 and 5), 

 with a smal oval ojjening high up near the urethra corresponding to the 

 hymeneal orifice. Its epithelium and connective tissue are vaginal. 

 Papillary proliferations are found on its inner and outer surfaces. 



The evidence of these five embryos can be briefly summarized as 

 follows : 



Fig. 5. Median sagittal section (Embryo 5). Section No. 187. F.. fold; 

 H., hj'men ; R., ventral wall of rec-tum ; S., sphincter ani nuiscle ; U., urethra ; 

 v., vagina. Magnified 5 X. 



In the fetus 18 cms. long (Embryos 1 and 2) there may be seen at the 

 point of junction of vagina and sinus urogenitalis, rising mostly from 

 the dorsal wall, a crescentic fold composed of elements coming both 

 from the vagina and the vulva or sinus urogenitalis. Occasionally, as 

 in Embryo 3, this fold is absent. In the fetus 21 cms. long this 

 crescentic fold is again to be seen, Init not so well marked. Anterior" 

 to it and lying wholly within the vagina is a thick membrane, the 

 hymen, almost completely closing the vaginal canal, composed only 

 of vaginal elements. No other similar folds or membranes are present. 



In the fetus 25-30 cms. long the crescentic vulvo- vaginal fold is still 

 recognizable, but the true hymeneal membrane is evidently anterior to 



