This process starts with double fertilization in angiosperms and it involves the fusion of the egg and sperm nuclei into a zygote. (sciencedaily.com)
This flexibility might help explain why eggs use such an unusual mechanism: Microtubule organizing centers are also critical for bringing together the egg and sperm nuclei after fertilization. (discovermagazine.com)
«But the discovery of fossil sperm, complete with sperm nuclei, was totally unexpected. (sciencedaily.com)