A sperm, from the ancient Greek word σπέρμα (seed) and ζῷον (living being) and more commonly known as a sperm cell,'s the haploid cell that's the male gamete. It joins an ovum to form a zygote. A zygote's a single cell, with a complete set of chromosomes, that normally develops into an embryo. Sperm cells contribute half of the genetic information to the diploid offspring. In mammals, the sex of the offspring's determined by the sperm cell: a s… (More on Spermatozoon)