Meiosis. Light micrograph (LM) of a squash preparation of astacus ( crayfish) testis to show meiosis. Meiosis is the process in eukaryotic, sexually reproducing animals that reduces the number of chromosomes in a cell before reproduction. Many organisms package these cells into gametes, such as egg and sperm. The gametes can then meet, during reproduction, and fuse to create a new zygote (union of the sperm cell and the egg cell). Because the number of alleles (variant form of a gene) was reduced during meiosis, the combination of two gametes will yield a zygote with the same number of alleles as the parents. In metaphase shown here, the centromeres of the chromosomes convene themselves on the metaphase plate (or equatorial plate), an imaginary line that is equidistant from the two centrosome poles. Magnification: x 500 when printed at 10 centimetres tall.