Meiosis: Nuclear division that results in the formation of cells containing half the number of chromosomes of the adult cell.
The number of body cells of species that reproduce sexually remains constant. The number of chromosomes in the body cells is the diploid number. The human diploid number is 46.
When gametes (egg & sperm) are produced, a different type of division occurs - meiosis. this occurs only in special parts of the body such as the testes and ovaries in animals, and anthers and ovary in flowering plants.
During meiosis, the chromosome number is halved so human gametes have 23 chromosomes - one of each type. The number of chromosomes in gametes is the haploid number. The human haploid number is 23.
The reduction in chromosome number ensures that at fertilisation, when the gametes fuse to form a zygote, the diploid number of chromosomes is restored.
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