During meiosis I, the 78 chromosomes in a diploid cell line up at the equator of the cell. Note that the chromosomes have already replicated.
39 chromosomes will then move to each pole of the cell. The difference between anaphase in meiosis I and mitosis is that in meiosis I, the centromere does not split, so the sister chromatids are still held together.
The result is 39 chromosomes at the poles of the cell. The chromosome number is reduced from 2n (diploid) to n (haploid). Then the cell will undergo meiosis II, where the cell will divide, producing 4 haploid daughter cells with half the number of chromosomes of the parent cell.
