What occurs during Metaphase I of meiosis?

During Metaphase I of meiosis, bivalents, which are pairs of homologous chromosomes, align along the metaphase plate in the center of the cell. This is a critical step in ensuring that each daughter cell receives one chromosome from each homologous pair. The arrangement of bivalents is facilitated by the microtubules of the spindle apparatus, which attach to the kinetochores of the chromosomes. This alignment allows for genetic variation, as the orientation of each pair can be random, promoting independent assortment of chromosomes.

The other processes listed occur at different stages of meiosis. Chromosomes condensing occurs in prophase I as the chromatin becomes more tightly packed. The separation of sister chromatids takes place during anaphase II, not metaphase I, when the duplicated chromosomes pull apart. The reformation of the nucleus and cell division happens during telophase and cytokinesis, completing the meiotic process.