XVI International Botanical Congess
Sperm (SC) are formed in pollen or tubes by two mitotic divisions of haploid microspore.The generative cell (GC) divides, later divide producing two SC. The SC are unique plant cells with specialized features: microtubular (Mt) bundles, condensed chromatin, small cytoplasm volume and absence of wall. Flowering plant SC differ from SC of non-seed plants and animals as they laks flagella. In SC and GC bundles of Mts with predominatly axial orientation, branch and region forming twisted basked or cage of Mts bundles in the thin cyoplasm surrounding the nucleus. Mts have arms resembling curved dynein arms of flagella, they exhibit arrangements, including bridges between Mts, between a Mt and vesicle or plasma membrane. The cytoskeleton of SC develop from the cytoskeleton of GC. SC and GC movement appear to be generate by cytoskeleton proteins present in pollen tube.