SUMMARY. Cytomixis and chromosomal polymorphism of micro-sporocytes in microsporogenesis of species Lilium cro-ceum Chaix., Allium fistulosum L. and A. cepa L. were studied. It was found that the main cytomictic events are associated with the early prophase of meiosis and are obligatory (constitutive) for the studied species. In metaphase microsporocytes, the so-called extra-chromosomes, presumably of cytomictic origin, were identified. They are characterized by the disintegration of homologues and associations with bivalents of the basik ka-ryotype with the formation of secondary associations of chromosomes. Extra chromosomes are present not only in hyperchromosomal, but in eu- and hypochromosomal microsporocytes. The most of extra chromosomes seem to be the «genetic ballast» for the cell, which it gets rid of using a wide range of cellular tools, in particular: chromosomal rearrangements, chromatin diminution, asymmetry of division, cytomixis, and programmed cell death. Nevertheless, some extra chromosomes can participate in the rearrangement of the microsporocyte and microspore karyotype.
Keywords: microsporogenesis, cytomixis, extra chromosomes, secondary chromosome associations, chromatin diminution, Lilium croceum Chaix., Allium fistulosum L., A. cepa L.
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