The human sperm cell is haploid, so that its 23 chromosomes can join the 23 chromosomes of the female egg to form a diploid cell. In mammals, sperm develops in thetesticles and is released from the penis. It is also possible to extract sperm through TESE. The spermatozoa of animals are produced through spermatogenesis inside the male gonads (testicles) via meiotic division. The initial spermatozoon process takes around 70 days to complete. However, competition not only exists among sperm, but also exists among eggs. Parker provided no explanations for why it was sperm that became smaller but not eggs, or what caused proto-sperm and proto-eggs to be unequal. In fact, a recent mathematical model[6] shows that sperm competition is neither necessary nor sufficient for the evolution of anisogamy. The ovum contains nearly all of the materials that will be needed by the zygote after fertilization, but it typically cannot move. The sperm contains almost nothing but the male genetic contribution to the zygote, but it is usually tasked with all of the travel necessary to bring the respective gametes together. In male humans, sperm cells consists of a flat, disc shaped head 5 µm by 3 µm and a tail 50 µm long. The tail flagellates, which propels the sperm cell (at about 1–3 mm/minute in humans) by whipping in an elliptical cone.
