Chromosome Pairing: Effect of Colchicine on an Isochromosome

Abstract

Two separable stages in the process of chromosome pairing have been demonstrated. The first results in a close spatial relationship of homologs, and the second results in synapsis and formation of chiasmata. Colchicine reduces chiasma formation in conventional bivalents but not in an isochromosome. Thus, colchicine affects only the first stage of pairing.