The sperm's head contains the fathers genetic contribution to the offspring. Inside, is the haploid amount of chromosomes inside the sperm head's nucleus. If it is a human sperm cell, the sperm head contains 23 chromosomes. The midpiece of the sperm cell contains fuel packets to provide the energy needed for the tail to move back and forth. The tail is actually a flagellum. It is composed of microtubules that form a bundle that can move in a whip-like motion. Its purpose is to propel the sperm up to the oviduct to join with an ova. If it should reach the ova, the midpiece and tail break off and the head which has enzymes will make its way into the haploid egg. Here, the nuclei of the two gametes fuse and fertilization occurs.