XVI International Botanical Congess

Sperm cells of pteridophytes exhibit remarkable diversity from biflagellated and slightly coiled (most lycophytes) to multiflagellated and highly coiled (ferns, Equisetum and psilophytes). Although the homology of sperm cells is unquestionable, the evolutionary status of specific cellular features such as flagellar number remains problematic. In this presentation, features of spermatogenesis will be compared among pteridophytes. Descriptive and experimental studies of development will be discussed, including mechanisms of cytoplasmic deletion, nuclear shaping and locomotory apparatus ontogeny. Information will be presented on the organic constituents of the locomotory apparatus and associated structures. These developmental and biochemical data enable an accurate evaluation of structural homology and provide insight into evolutionary modifications of plant sperm cells.