01547nas a2200169   4500008004100000022004300041245009200084210006900176260005600245300001400301490000700315520087200322100001501194700001801209700002601227856012401253       2006                        eng d  a0214-6282 (Print); 0214-6282 (Linking)00aEgg development in parthenogenetic nematodes: variations in meiosis and axis formation.0 aEgg development in parthenogenetic nematodes variations in meios  aZoologisches Institut, University of Koln, Germany.  a393–3980 v503 aIn the well studied model nematode Caenorhabditis elegans entrance of the sperm induces an anterior-posterior polarity in the egg and determines the orientation of the primary embryonic axis. Subsequently, fusion of two haploid gamete nuclei results in a diploid zygote as a prerequisite for normal embryogenesis. Here we analyze the establishment of embryonic polarity and diploidy in the absence of sperm in three parthenogenetic nematode species from three different families, Diploscapter coronatus (Diploscapteridae), Acrobeloides nanus (Cephalobidae) and Plectus sp. (Plectidae). We find that they not only differ from C. elegans in these two aspects but also from each other, indicating variant solutions for the same developmental challenges and supporting the view that the parthenogenetic mode of reproduction has been acquired multiple times independently.1 aLahl, Vera1 aSadler, Bernd1 aSchierenberg, Einhard  uhttps://nematoda.myspecies.info/content/egg-development-parthenogenetic-nematodes-variations-meiosis-and-axis-formation