 mammalian sperm carry not only the paternal genome but also the paternal epigenome in the form of DNA methylation, retained histones, and non-coding RNAs. These epigenetic marks have been linked to protein-coding genes that are critical for pre-implantation embryonic development, although there is no evidence that they play a role in fertilization and early development. Two menoclusters consisting of five menors, MIR, 34B, C, and MIR for 49A, B, C, are found in sperm, but absent from acytes. MIR, 34C has been shown to be necessary for the first cleavage division in vitro, while MIR, for 49A, B, C are essential for normal fertility. Intracytoplasmic injection of A the MIR, 34B, C, or MIR, for 49, null sperm leads to normal fertilization, normal pre-implantation development, and normal birth rates. However, MIR, 34B, C, and MIR for 49 double knockout, MIR-DKO. This article was authored by Shu H. G. Luang, Zhong Tang, Ying Zhong, and others. We are article.tv, links in the description below.