
Schematic representation of acrocentric chromosomes that depict the inter-chromosomal exchanges in the rDNA sequences among (1) nonhomologous and (2) homologous chromosomes, and (3) intra-chromosomal exchanges among rDNA sequences within a single chromosome. These exchanges are likely to be the cause of the extensive variation in rDNA copy numbers and the homogenization of these sequences among the alleles of all five acrocentric chromosomes.











