Efficient human sperm pronucleus formation and replication in Xenopus egg extracts

We have achieved efficient in vitro reactivation and replication of human s perm nuclei in frog egg extracts by constructing a 4-step protocol that mim ics the events of fertilization and pronucleus formation in mammalian eggs. With use of this protocol, 78-97% of human sperm nuclei from fertile donor s synchronously swelled and completed full genome replication in about 2 h. We document the changes in nuclear structure that accompany efficient DNA synthesis and discuss future research and potential clinical implications o f this new system.