noun, plural: sperm cells
A single sperm cell consists of a round or cylindrical nucleated cell, a short neck, and a thin motile tail. Its structure is vital to its mobility and function (i.e. sexual reproduction). The compacted nucleus contains half of the genetic information. It fuses with an ovum (the female gamete) to form a zygote. In mammals, the sex is determined by the sperm cell. If it bears Y chromosome, the resulting offspring is a male. If X chromosome, the offspring is a female.