93 Fred. J. Taussig 



hymen. It was this fact that induced me to study the five embryos at 

 my disposal by this method. They were the following: 



Embryo 1. 18 cms. long, well preserved. No abnoruialities of de- 

 velopment as far as examined. 



Embryo 2. 18 cms. long, slightly macerated, no abnormalities. 



Embryo 3. 18 cms. long, well preserved, normal. 



Embryo 4. 21 cms. long, removed by laparotomy, excellent preserva- 

 tion. No abnormalities in development. 



Embryo 5. Six months gestation. Legs have been removed for 

 another purpose, hence exact length could not be determined. Preserved 

 in Mueller's fluid. No abnormalities of development. 



The measurements of these embryos were taken from the vertex to 

 the heel. 



[/ 



Fig. 1. Median sagittal section at entrance of vagina into urogenital sinus 

 (Embryo 1). It is seen tliat the fold at tlie entrance is in connection partly 

 with the vagina, partly with the sinns. F., fold ; U., urethra ; U. S.. uro- 

 genital sinus ; V., vagina. Magnified 20 X. 



Paraffin was used in Embryo 1, celloidin in Embryos 2, 3, 4 and 5, as 

 an imbedding medium. All sections were cut sagittally, in series, 25 

 microns in thickness and were stained, some with van Gieson, some with 

 hematoxylin and eosin. 



Before proceeding with the description of the microscopic findings, 

 it will be well to point out the difference between the epithelium of the 

 vagina and that of the urogenital sinus. Sinus epithelium as usually 

 seen in section is a narrow, deeply staining band of small, round or 

 spindle cells, with a nucleus almost filling the cell, whereas vaginal 

 epithelium is a wide mass of large polygonal, faintly staining cells. 

 Only the basal cells of the vagina are small and these take a deeper 

 stain (see Fig. 8a). Klein gives the following measurements: 



