Sperm cannot develop if the testis is at body temperature. The pampiniform plexus helps to regulate testicular temperature, allowing sperm maturation. The plexus surrounds the testicular arteries and works as a countercurrent heat-exchange system to cool the arterial blood before it enters the testis. Along with the pampiniform plexus of veins, temperature in the testis is controlled by sweat glands on the scrotum and by the cremaster muscle, which controls the proximity of the testis to the body.