The Y chromosome carries a gene on its sho arm that codes for
Testosterone
MIF
Testes-determining factor (TDF)
Progesterone
The SRY (sex region Y chromosome) gene present on the sho arm of the Y chromosome codes for TDF (Testes Determining Factor). Presence or absence of this chromosome decides whether the fetus will be male or female. Sex determination is not possible till week 6 i.e. why the embryo is called indeterminate embryo till week 6. External sex differentiation completes after week 11. USG sex determination can be done at this time.
Development of GU system and Neuro-vascular supply of pelvis & perineum