96 • Fred. J. Taussig 



from surrounding structures. We find the connective tissue fibres more 

 developed and an admixture of unstriped muscular fibres. 



Following the vagina down to its point of entrance into the sinus 

 urogenitalis, we are struck by the difference in size and staining property 

 of the vaginal and sinus epithelium. The sinus epithelium at this point 

 consists of three or four layers of small cubical cells with deeply stain- 

 ing nucleus. This difference in the epithelium, already emphasized by 

 Klein, together with the direction of the connective tissue fibres, makes 

 it easy to determine how much is vagina, how much is sinus. 



It is seen in studying the series that a crescentic fold of tissue 

 attached to the dorsal and lateral aspect is left at the point of entrance 

 of vagina into sinus. This fold is lined on the inner side by vaginal, 

 on the outer side by sinus epithelium (Fig. 12). It is not by any means 

 a well-formed membrane. 



Just anterior to this fold the connective tissue of the vagina both 

 ventrally and dorsally (but principally dorsally) sends a proliferating 

 branch in through the epithelium. The two join to form a membrane 

 that, with the exception of one small opening, completely closes the 

 vaginal canal. It is clear that this membrane must be the hymen, and 

 it is also indisputable that, in this case at any rate, it is of vaginal 

 origin, since it lies internal to the point of junction between vagina and 

 sinus urogenitalis, is lined on both sides by vaginal epithelium, and has 

 its connective tissue directly continuous with the connective tissue of 

 the vagina. 



That this membrane is not one of the secondary folds occasionally to 

 be seen internal to the hymen, Avliere there is a marked proliferative 

 tendency on the part of the vaginal connective tissue, is evident by the 

 fact that (with this one exception) there are to be seen no high papillary 

 jDrojections. The sections in this case seem to represent about the same 

 stage of development as do those of Klein, but his interpretation of the 

 findings is different, as will be subsequently shown. 



Embryo 5 {Figs. 4-8). Development that of about 5-6 months. The 

 vagina is 3 cms. in length and from 2-6 mms. in diameter. The 

 narrowest portion is the upper fifth, in which there is no lumen and 

 the epithelium is only a few layers of cells in thickness. Here there 

 is also little connective tissue proliferation. Further down the canal, 

 and particularly near the vulvar end, this proliferation is very extensive, 

 so that there appear bands, papillae and islands, depending on the way 

 the sections happen to be cut through the projections. Here we should 



