This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: External Genitalia, Subject name: Gynaecology & Obstetrics
Vagina develops from: 
Select and explain. 
A. Mesonephric duct, B. Genital tubercle, C. Urogenital sinus, D. None of the above
C: Urogenital sinus
Answer: C: Urogenital sinus 
Explanation: Ans. a) Urogenital sinus Ref Novak's 14th ed Pg 100Vagina forms in the 3rd month of embryonic life.Superior part of vagina from - paramesonephric ductInferior part of vagina from - sinovaginal bulb on the posterior wall of urogenital sinus.Sex is not apparent until about 12th week of embryonic life.