Regulative germ cell specification in axolotl embryos: a primitive trait conserved in the mammalian lineage.
Andrew D Johnson, Brian Crother, Mary E White, Roger Patient, Rosemary F Bachvarova, Matthew Drum, and Thomas Masi
Philos Trans R Soc Lond B Biol Sci. 2003 August 29; 358(1436): 1371–1379. doi: 10.1098/rstb.2003.1331.PMCID: PMC1693234