The energy used by sperm to move up the fallopian tube is stored in the epididymis of the sperm's midpiece. The epididymis is a tube located at the back of the testicles. During ejaculation, the sperm move from the lower part of the epididymis. They have not been activated by products from the prostate gland yet, and they are not able to swim. However, they are transported through the peristaltic action of muscle layers within the vas deferens. They are mixed with the diluting fluids of the seminal vesicles and other accessory glands before ejaculation.
