Which cells undergo meisois???

Gametes are produced by meiosis. What happens is the cells in the reproductive organs are regular diploid cells. They undergo the regular process of mitosis, but then when two identical cells are produced, the chromosomes are not copied as they usually are in mitosis, and they are each split into 2 new cells with half the chromosomes. Later when the egg is fertilized by the sperm, they each contribute half the chromosomes to make the full set of chromosomes required for a diploid cell, which then undergoes mitosis to form a new organism.