tetraploid

An organism or cell with four times the haploid number of chromosomes. The fusion of diploid gametes will result in the formation of a tetraploid. Such gametes initially arise because of the failure of homologous chromosomes to separate at meiosis. Alternatively a tetraploid segment of a plant may arise because of the failure of chromatids to separate at mitosis. If this segment develops reproductive structures then diploid gametes will be formed. See autopolyploidy , allopolyploidy.