Why have my testes descended completely?

Q: I am a 30 year old man. I have been masturbating for about 15 years. When I was 17 years old, my testes had completely descended. Now my penis is very small, about 2 inches and my testes hang very low at a relevant distance from the penis. Will this affect my sterility? When I go to the toilet and apply pressure, my testes go up and become hard and rigid. But after about 20 minutes, it again comes down. Please advise.

A:The scrotum is an external sac containing the testes that holds them outside of the body to keep sperm 4-5 F cooler than the body temperature. Testicles are temperature sensitive organs that produce sperm and this production is temperature dependent. Inside the scrotum are muscles (cremaster and dartos) that are affected by temperature. When there is warmth, the muscles relax and drop, making the scrotum and the testicles hang lower. Cold makes them contract. It is normal for the scrotum to go through these changes, and is not a problem. This functions to keep the testes warm and protect them from injury. You should not be worried as this is normal.