ABSTRACT
A comparative cytological analysis of intra- and intertissular cytomictic interactions in early micro-sporogenesis of mono- and dicotyledonous plants was performed by the example of the two cellular systems - microsporocytes and tapetum. It is found that cytomixis is the component of intratissular interactions mainly. In the tapetum cells cytomixis is notable for structural and temporary taxon specific features. The nuclear migration in microsporocytes is confined mainly to zygotene-pachytene meiotic stages and characterized by a certain synchronism with cytomixis at the tapetum. Intertissular cytomictic interactions (tapetum - microsporocytes) were found in the monocot anthers only. Intertissular interactions are likely to reflect the intensification of competitive relations between the tapetum and microsporocytes for area in the process of anther tissue differentiation. Polyploid tapetum nucleus and syncytia being powerful acceptors are able to compete with microsporocytes and direct the chromatin translocation to their favor. The absence of intertissular interactions in dicots probably reflects a better balance between the processes of differentiation at somatic and generative tissues into microsporangium compared to monocots.