[Two routes for the development of chromosome aberrations]

Data on cytogenetic investigations using the method of influence of DNA and protein syntheses inhibitors on the chromosome are summarized. The formation of chromosome rearrangements and gaps is considered to be due to the appearance of DNA damage. The formation of these changes is proved to be similar under radiation and chemical mutagenesis. Successive stages of the realization of chromosome aberrations are united by crossing over (contact) hypothesis. The other was of the formation of cytogenetic changes is due to DNA structural degradation. These two ways can combine in radiation and chemical mutagenesis (depending on doses and mutagens).