Practice question

While Briggs and King showed frog nuclei retained developmental potency in amphibians, mammalian genomic equivalence required additional technical advances due to small eggs and implantation requirements. Ian Wilmut and colleagues at Roslin Institute provided definitive mammalian proof by creating Dolly from adult mammary cell nucleus. Surrogate mother carried embryo to term, and microsatellite analysis confirmed genetic identity to donor, not egg donor. Earlier claims by Illmensee and Hoppe about mouse cloning proved irreproducible. Therefore mammalian equivalence first convincingly demonstrated by Wilmut, extending Gurdon's amphibian principle to endothermic vertebrates with placental development.