This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Malformation of the Female Generative Organs, Subject name: Gynaecology & Obstetrics
All of the following take part in male genital tract development except 
Select and explain. 
A. SRY, B. SOX-9, C. FGF-9, D. WNT-4
D: WNT-4
Answer: D: WNT-4 
Explanation: Ans. is d, i.e. WNT-4Ref: Langman Embryology 12th/ed, p46-247Genes for male developmentSRY geneMaster Gene for testis developmentSOX 9SRY and SOX 9 induce testis to form FGF-9 (chemotactic factor). FGF-9 causes tubules from mesonepric duct to penetrate gonadal ridgeSF1 (steroidogenic factor)It stimulates differentiation of sertoli or leydig cellsWNT-4 is ovary determining gene. This gene upregulates DAXI which inhibits the function of SOX 9 in females.