into the epididymis
After spermatids form, they move into the epididymis to mature into sperm, like the one shown in Figure below . The spermatids grow a tail and lose excess cytoplasm from the head. When a sperm is mature, the tail can rotate like a propeller, so the sperm can propel itself forward. Mitochondria in the connecting piece produce the energy ATP needed for movement. The head of the mature sperm consists mainly of the nucleus, which carries copies of the fathers chromosomes. The part of the head called the acrosome produces enzymes that help the sperm head penetrate an egg.