The pairing center plays a key role in homolog paring: an explanation for adjacent-2 segregation in interchange heterozygotes.

Having reflected on the discrepancy between various views of chromosome behavior during meiosis, we propose an alternative description of Mendel's first law of segregation by referring to the segregation of pairing centers instead of centromeres. We also propose an alternative description of Mendel's second law of independent assortment, which refers to the free combination of different pairing centers. This interpretation is based on the modified concept that true 'homologous chromosomes' should carry the pairing center rather than centromere: the length of homology or the importance of the homologous segment on the chromosome is the crucial factor in homologous chromosome pairing and synapsis.