Customer Service is our #1 Priority! We take pride in providing services around the clock for U.S. citizens who need a passport fast. We provide this excellence in service by allowing you to access a passport specialist over the phone.
Male sperm cells in humans and other mammals are heterogametic and contain one of two types of sex chromosomes. They contain either an X chromosome or a Y chromosome. Female egg cells however, contain only the X sex chromosome and are therfore homogametic. The sperm cell determines the sex of an individual. If a sperm cell containing an X chromosome fertilizes an egg, the resulting zygote will be XX or female.
Humans have 46 chromosomes in each cell. During fertilization of the egg, the sperm nucleus containing 23 chromosomes from the paternal side fuses with the nucleus of the egg that contains 23 chromosomes from the maternal side. The result is the zygote that contains 46 chromosomes (23 pairs of chromosomes; one of each pair from either parent). From that single celled zygote comes all the cells of your body today that is formed as a result of uncountable number of cell divisions.