Cytological markers of rRNA gene expression during microsporogenesis in rye, wheat and wheat-rye hybrids

The quantity of nucleolei during microsporogenesis of wheat, rye and F1 of wheat-rye hybrids has been investigated. Dependence of nucleoli quantity from microsporogenesis stage and number of nucleolar organizer regions in chromosomes have been shown. The volumes of nuclei and nucleoli as well as nucleus-nucleolus ratio have been calculated. The changes of these indices during microsporogenesis were regular. The possibility of using cariometrical indices as cytological markers of rRNA gene expression in the process of microsporogenesis has been substantiated.