XVI International Botanical Congess

Vegetative thallome of Vaucheria sessilis is formed as a result of the aplanospore germination. The treatment with cytochalasin, and colchicine prevented germination of aplanospores.Four stages in morphogenesis were identified. Nuclear division starts before the appearance of germinative changes, and mitoses occur until the formation of vegetative thallomes takes place. Actin formed net of shot single microfilaments, microtubules aggregated in paralell bandes under cytoplasmic membrane at the begining of germination. Simultaneously with nuclei migration into the forming branch reorganization of the cytoskeleton occured. The end of germination is characterized by formation of cortical fibers of microfilaments, shot bundles of micotubules associated with nucleus, network of shot actin filaments in the apical zone.