Reproductive biology: delivering spermatozoan RNA to the oocyte

Even though the genetic fingerprint of human sperm has been defined, its role in orchestrating fertilization and the development of the early embryo remains vague. Here we show that human male gametes pass over more to the oocyte than just the haploid male genome--paternal messenger RNAs are also delivered to the egg at fertilization. If these transcripts, previously thought to be left-overs from spermatogenesis, are important in early development, our findings may have implications for the success of somatic-cell nuclear transfer in cloning technology and the identification of components leading to unexplained male-factor infertility.