In prophase I of meiosis I, there are 5 sub-stages. The first one is leptotene where the chromosome starts to condense. Followed by zygotene was the pairing of the homologous chromosome and become closely associated during synapsis and the formation of the Synaptonemal complex. The third sub-stage is pachytene were the crossing over occur, forming chiasmata, which hold homologous chromosome together. In diplotene, the Synaptonemal complex start to disappear and in the last stage, diakinesis, the Synaptonemal complex is completely disappearing.

In metaphase I, the pair of homologous chromosome aligns along the metaphase plate in double row. The formation of chiasmata before are to help keep the pairs together and position the pairs such that only one side of each homologue’s centromere faces outward toward of the cell’s poles. Thus kinetochore microtubules attach to only one side of each centromere; a kinetochore microtubules from one pole of the cell attaches to one homologue of the chromosome while a kinetochore microtubules from the other cell poles attaches to other homologue.

In anaphase I, kinetochore microtubules shorten and homologous pairs are pulling apart. One duplicated homologue goes to the other poles. Sister chromatids do not separate. This is in contrast to mitosis, where duplicated homologues line up individually on the metaphase plate, kinetochore microtubules from opposite poles of the cell attach to opposite sides of one homologue’s centromere, and sister chromatids are pulled apart in anaphase.

In telophase I, the separated homologues form a cluster at each poles of the cell, and the nuclear membrane re-forms around each daughter cell nucleus. Cytokinesis may occur. The resulting two cells have half the number of chromosome as the original cell. Each chromosome is still in the duplicated state and consists of two sister chromatids, but