Meiosis

Meiosis is the means by which the chromosome number of the sex cells (spermatozoa and ova) is reduced from the diploid number to one-half that number - the haploid number. The chromosomes do not double before pulling apart. Half the chromosomes go to each daughter cell in a random fashion. This is how nature "shuffles the genetic cards." When an ovum is fertilized by a spermatozoon, the diploid chromosome number is restored in the resulting offspring.