Why do my testis disappear when I get an erection?
Q: I am a 25 years old male. I have observed that my testis have shrunken a bit
A:Testis are attached to body with structure containing muscles, called cremasteric muscle, which contract and relax to bring testis close to or away from body depending on body and atmospheric temperature. Even touching inner part of thighs may induce cremasteric muscles to contract (creasteric reflex) and thus make them "disappear". Semen amount varies, and would be smaller if ejaculations are frequent.