MOKPHOLOGY OF THE HUMAN URINOGENITAL TEACT. 371 



DESCRIPTION OF PLATES XXXV., XXXVI. 



Fig. 1. Vertical mesial section of caudal end of 4-2 mm. foetus 

 (Keibel). Xote formation of primitive gut with Wolffian duct open- 

 ing into posterior part : cloacal membrane, a, is anterior boundary 

 of entodermal cloaca (pars penultima of primitive gut) ; tail gut, 6, 

 present. 



Fig. 2. Blastula stage of Amphioxus (Hatschek), 2^-5. 



Fig. 3. Gastrula stage of Amphioxus (Hatschek), 2 2.o_ 



Fig. 4. Dorsal view of 2 mm. human embryo, ^. P.S., primitive 

 streak; N.T., neurenteric canal entering yolk sac; N.G., neural 

 groove; H.P., head end of embryo, ^ (Graf Spee). 



Fig. 5. Embryo, H.s./., 6-5 mm., ; a, tail gut withering; h, ureter 

 budding off from Wolffian duct (Keibel). 



Figs. 6-9. T.S. of 4-2 mm., human embryo, showing stages of 

 division by coronal partition of primitive gut into rectum and bladder 

 (Keibel) ; r, rectum ; b, bladder. 



Fig. 10. To show view that bladder originates from allantois (Allen 

 Thomson), r, rectum ; b, bladder ; ii.g.s., urinogenital sinus. 



Fig. 11. Genital cord in 6-7 weeks embryo (30 mm.), showing in 

 front the urinogenital sinus with eminence of Mliller, below which 

 the hymen forms (T.S.); s, urinogenital sinus; W, Wolffian duct; 

 m, duct of Midler. 



Fig. 12. Genital cord immediately below that of fig. 11 (T.S.) 

 shows urinogenital sinus with Wolffian ducts opening into it. This 

 is site of future hymen. 



Fig. 13. Genital cord below that of fig. 12 (T.S.), to show Anlage 

 of H-shape of adult vagina near vaginal orifice ; urinogenital sinus in 

 front, and behind, Wolffian ducts on each side of canal of coalesced 

 Miillerian ducts. 



Fig. 14. T.S. of 6-7 weeks embryo to show kidney and Wolffian 

 body. /,-, kidney ; W.B., Wolffian body. 



Fig. 15. T.S. of 6-7 weeks embryo to show ovary formed on Wolf- 

 fian body. 0, ovary ; W.B., Wolffian body. 



Fig. 16. Vertical mesial section of foetal rabbit, 10 mm., 13th day, 

 to show primitive gut with partition forming to divide off bladder and 

 rectum, and passing down to meet epidermic plug (Eetterer). 



Fig. 17, Vertical mesial section of tail end of rabbit, 14th day, 

 showing division of primitive gut into rectum and bladder, and union 

 of partition vrith epidermic plug (Eetterer). e.^?., epidermic plug. 



