Androgen binding protein which helps in concentrating testosterone in the seminiferous tubule, and which inhibits $ICSH$ secreted by anterior pituitary and $GnRH$ production by hypothalamus is secreted by
Cells of Leydig
Sustentacular cells
Interstitial cells
Spermatogonial cells
The fifth cleavage of the fertilized egg of frog results in the formation of
The phenomenon of fertilization was first perceived by
Which of these is used to control human population?
Vaginal orifice, urethral orifice are open in
How does zona pellucida of ovum help in preventing polyspermy ?