MORPHOLOGY OF THE HUMAN UEINOGENITAL TRACT. 363 



VJl. The PiELATioN of the Views Advanced to Certain 

 Developmental Arrests in the Upjnogenital Tract. 



I take up only those cases which are, for whatever reason, 

 permanent developmental arrests, and I consider vspecially only 

 some of the rarer ones which have come under my own personal 

 observation. For clearness, however, I shall repeat a resume of 

 normal developmental stages. Normal development may be 

 summed up as follows : — ■ 



Stage. Date. 



1. Division of primitive gut into bladder, 



rectum, and urinogenital sinus ; cloacal 

 membrane present ; withering of end 

 gut (pars ultima), .... 20th to 23rd day. 



2. Communication of pelvic end of urethra 



and rectum with exterior by formation 

 of ectodermic pbig ; its breaking down, 

 and thus existence of ectodermic cloaca, 4th to 6th week. 



3. Closure of cloaca by Reichel's Anal- 



hocker, 7th to 8th „ 



4. Urinogenital sinus completely formed 



with ducts of cruller related to it, and 



Wolffian ducts opening into it, . . 8th to 9th „ 



5. Hymen formed, anus formed, preputium 



cUtoridis in course of formation ; 



Miillerian vagina being relined from : 



Wolffian bulbs, .... 3rd and 4th month. 



I need not recapitulate the well-known facts as to the appear- 

 ance of the ducts of Miiller, and their time of fusion so as to 

 form the uterus and tubes {vide Hart and Barbour, 5th edit,, 

 p. 291). 



The special malformations I have been able to study belong 

 mainly to the rarer forms, and comprise — 



1. Fast us without urinogenital system. 



2. A pediculated tuntour attaehed to the perineal region of a 



female infant, which on removal and mirro.-^copiral exanmia- 

 tion proved to he a piece of iwlated ho'w el, probably persistent 

 end-gut. 



3. Two cases of transverse septum vagiius dividing the vagina 



into a lower third and upper two-thirds. 



4. A case of atresia of the loicer third of the vagina, the rest of 



the tract being developed. 



