title: Counterfeiting the family jewels.
abstract: In art and literature, originals are revered and copies frowned upon. But do men use germline stem cell copies to pass traits to their children? In Science, Nakagawa et al. (2010) show that new stem cell copies regularly arise in mouse testes by fragmentation of downstream germ cell clusters.
authors.affiliation: Department of Embryology, Carnegie Institution, Baltimore, MD 21218, USA.
authors.forename: Allan
authors.initials: A
authors.lastname: Spradling
authors.forename: Chen-Ming
authors.initials: CM
authors.lastname: Fan