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Researchers transplanted cells between embryos of a comb jelly (Mnemiopsis leidyi, right) and a starlet sea anemone (Nematostella vectensis, left).Credit: Paul R. Sterry\/Nature Photographers Ltd\/Alamy, Phil Degginger\/Science Photo Library<\/p>\n
More than a century ago, embryologist Hilde Mangold conducted a strange experiment that transformed biology. <\/p>\n
As a PhD student in the 1920s, she moved a lump of cells from embryos of one newt species into another. The transplanted cells caused a secondary \u2018body axis\u2019 to form in the host embryo, complete with a nervous system and a precursor to the spine. Mangold showed that much of the secondary body axis developed from the recipient embryo tissues.<\/p>\n
The discovery of an embryonic \u2018organizer\u2019 that orchestrates the formation of a body axis \u201cestablished a whole new area of developmental biology\u201d, says Stanislav Kremnyov, a developmental biologist at the Friedrich Schiller University Jena in Germany, who is now following in Mangold\u2019s footsteps. <\/p>\n
In a study published in Nature on 17 June1<\/a>, Kremnyov and his colleagues report the discovery of an embryonic organizer in marine predators called comb jellies (Ctenophora) and their successful transplantation into sea anemones (Cnidaria) \u2014 which belong to an entirely different phylum \u2014 forming extra mouths and pharynxes.<\/p>\n Many scientists think comb jellies belong to the earliest branch of the animal family tree. Kremnyov and his colleagues argue the appearance of an organizer helped transform single-celled organisms into animals.<\/p>\n \u201cI\u2019m really excited to see this,\u201d says Ulrich Technau, an evolutionary developmental biologist at the University of Vienna. But not all scientists are convinced by the claims.<\/p>\n Building a second body<\/p>\n Mangold died tragically in 1924 in a home gas explosion, but the discovery garnered her supervisor, Hans Spemann, the 1935 Nobel Prize in Physiology or Medicine.<\/p>\n Spemann\u2019s laboratory became the centre of the developmental biology world, attracting leading scientists to probe the organizer and look for similar capabilities in other developing tissues.<\/p>\n Ancient sea jelly makes tree of life wobble<\/p>\n <\/a><\/p>\n \u201cThey did insane things,\u201d says Kremnyov, transplanting tissue from snails and mouse kidneys into frog embryos, showing that these, too, possessed organizational activity. Later, in the 1980s and 1990s, scientists uncovered the molecular basis for organizers: signalling molecules known as morphogens.<\/p>\n Kremnyov says that that organizer cells and the morphogens they release act like a construction foreman in the developing embryo, telling \u201cthe cells what they have to do and what they have to build\u201d.<\/p>\n Research into the organizer has been focused mostly on vertebrates. But in 2007, a team led by Technau discovered such cells in the embryos of starlet sea anemones (Nematostella vectensis)2<\/a>, which belong to an animal lineage that diverged after that of comb jellies. The findings raised questions about the evolutionary origins of the organizer.<\/p>\n \u201cUntil our work, it was not known when it emerged,\u201d says Kremnyov.<\/p>\n Hilde Mangold, shown here holding her baby, discovered embryonic \u2018organiser cells’ in 1924 during her PhD.Credit: Science Source\/Science Photo Library<\/p>\n Two mouths<\/p>\n Kremnyov\u2019s supervisor and study co-author, developmental biologist Andreas Hejnol at the Friedrich Schiller University Jena, maintains a menagerie of unusual invertebrates \u2014 including sea anemones, penis worms and flatworms \u2014 that he calls a microzoo. When he joined the lab, Kremnyov added a comb jelly (Mnemiopsis leidyi).<\/p>\n![\"\"](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2026\/06\/d41586-026-01910-0_51974144.jpg\"\/)
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