90 Fred. J. Taussig 



(1) Vulvar Theory. Pozzi ('84) bases his theory wholly on the 

 clinical findings in cases of malformation of the genital tract, above all 

 on the presence of a hymen in the absence of the vagina, the occasional 

 occurrence of a urethral hymen, and the presence of a single hymen in 

 double vagina. Such anomalies he believes could only occur if the 

 hymen developed from the vulva or sinus urogenitalis. 



(2) Bilamellate Yulvo-vaginal Theory. In 53 out of 190 specimens 

 of fetal hymens (28.8 per cent) Schaeffer ('90) was able to find a more 

 or less distinct double hymen. The two folds were connected by bands 

 of tissue, and according to his theory later coalesce to form the hymen. 

 The one fold springs from the vulva, the other from the vagina. Thus 

 we would have a four-layered hj^men, two layers from each fold. 



(3) Uni-lamellate Vulvo-vaginal Theory. Budin ('79) explains this 

 theory in the following way: The hymeneal ring is the outer end of the 

 vagina. The latter opens into the sinus urogenitalis, at the same time 

 pushing the walls of its canal outwards, just as the portio vaginalis uteri 

 protrudes into the vagina. Thereupon an opening forms in the centre, 

 but the peripheral ring-like protrusion remains, covered externally by the 

 mucosa of the urogenital sinus, internally by the vaginal mucosa. Nagel's 

 ('97) description (Fig. 9) differs only slightly from this. He says: "In 

 embryos of the third month there is an increase and accumulation of 

 the upper layers of the epithelium occurring at first just above the vaginal 

 orifice, whereby the vagina becomes dilated at this point (in embryos of 

 7-10 cms. length). Through this dilatation arises the hymen. For since 

 the edge of the original opening is not affected by the dilatation, the 

 orifice, on the contrary, retaining its original narrowness, a ring must 

 thereby be formed by which the vagina is shut off from the urogenital 

 sinus. The opening of this ring, up to embryos of 20-22 cms. length, 

 remains filled with epithelium." 



According to this view, therefore, the hymen is made up of a single 

 fold, one side of whieli is formed by the vagina, the other by the vulva. 



(4) Vaginal Theory. Dohrns ('75) work supporting this theory is 

 based on median sagittal sections through the pelvis of twenty-five 

 fetuses from the ninth to the twenty-eighth week of development. N"o 

 microscopic study Avas made. From the ninth to the fifteenth week he 

 finds a stronger growth of the posterior wall of the vagina so that its 

 canal becomes wider and bends more sharply forward. From the seven- 

 teenth to the nineteenth week there is a marked proliferation of the 

 inner wail of the vagina, so that it seems made up of tooth-like projec- 



