Though you may have heard otherwise, there isn't enough evidence to prove that this is the case.
Females can activate their testes and deactivate their ovaries.
Did you know that there are fish out there that can change sex?
Varicose veins in the legs occur when the valves in a vein near the surface of the skin malfunction. Valves usually keep blood from flowing backwards in the vein once it’s been pumped towards the heart.