Testicles are the male reproductive organs responsible for producing sperm and hormones, particularly testosterone. They are typically oval-shaped and located in a pouch of skin called the scrotum, which hangs outside the body. This external position helps regulate temperature, as sperm production requires a cooler environment than the body's core temperature. Each testicle contains seminiferous tubules where sperm cells are formed. Once produced, sperm travel through a series of ducts to mature and are stored in the epididymis. The testicles also play a crucial role in the overall male reproductive system, influencing traits such as muscle mass and body hair through hormone production.