Not just heads and tails: The complexity of the sperm epigenome.

Transgenerational inheritance requires mechanisms by which epigenetic information is transferred via gametes. Canonical thought holds that mammalian sperm chromatin would be incapable of carrying epigenetic information as post-translational modifications of histones because of their replacement with protamine proteins. Furthermore, compaction of the sperm genome would hinder DNA accessibility of proteins involved in transcriptional regulation and genome architecture. In this Minireview, we delineate the paternal chromatin remodeling events during spermatogenesis and fertilization. Sperm chromatin is epigenetically modified at various time points throughout its development. This allows for the addition of environment-specific modifications that can be passed from parents to offspring.