In a groundbreaking series of experiments conducted by researchers at the University of Jena, scientists have revisited and expanded upon a century-old discovery that shapes our understanding of embryonic development. Originally unearthed by Hans Spemann and his student Hilde Mangold in 1924, the concept of the “organiser” is a pivotal developmental mechanism that directs the formation of body axes during the early stages of an embryo’s growth. Spemann and Mangold’s pioneering work involved tissue transplantation between amphibian embryos, revealing the presence of a group of cells within the blastopore that orchestrate the development of a secondary body axis. This discovery earned Spemann a Nobel Prize in 1935 but tragically Mangold passed away young, never witnessing the lasting impact of their findings.
The new research from Jena not only reaffirms these foundational insights but extends them dramatically into the early evolutionary origins of metazoans. Using delicate microsurgical manipulation, the team studied the ribbed comb jelly Mnemiopsis leidyi, a member of the ancient phylum Ctenophora. This lineage diverged from that of other animals approximately 700 million years ago, according to the latest evolutionary models. By transplanting small portions of blastoporal tissue from one comb jelly embryo into another, Jena researchers induced a secondary body axis, effectively recapitulating Spemann and Mangold’s classic findings but now in one of the earliest-diverging animal lineages. The experiment demonstrated that the organiser’s developmental blueprint is deeply conserved across vast evolutionary time frames.
What makes these experiments particularly astounding is the technical difficulty involved. Comb jelly embryos measure only about 120 micrometers in diameter—just a fraction larger than the width of a human hair—while the transplanted tissue samples were barely 20 micrometers in size. Dr. Stanislav Kremnyov, the lead experimentalist, had to master an extraordinary level of manual dexterity to integrate these tiny groups of cells into host embryos without triggering rejection or other developmental derailments. To an outside observer, it appeared as if the researchers were “dissecting clouds,” a vivid metaphor used by Prof. Andreas Hejnol, who leads the research team at Jena.
The functional transplantation of organising tissue between individuals of the same species was spectacular enough. Yet the Jena team dared to push further by performing xenotransplantations, transferring organiser tissue across animal orders into the sea anemone, a cnidarian species that diverged from ctenophores roughly 60 million years later. Remarkably, the transplanted organiser tissue also initiated axis formation in the sea anemone embryos. This unprecedented success underscores the extraordinary evolutionary conservation of developmental mechanisms underpinning animal body plans. Xenotransplantation of organiser tissues across distinct phyla had never before been demonstrated, marking this as a historic advance in developmental biology.
Beyond the cellular choreography, the study also zeroed in on genetic underpinnings. The team identified, for the first time, the specific gene responsible for organiser formation in the sea anemone, bridging molecular mechanisms across species boundaries. This gene appears to regulate the signalling networks critical to early embryonic axis determination, providing a molecular anchor to the organiser’s functional role. Such findings hint that the genetic toolkit necessary for complex body plan organisation was already present in the earliest multicellular ancestors of modern animals.
These discoveries overturn previous assumptions that organiser-driven axis formation was a feature exclusive to more recently evolved animal groups such as bilaterians. Instead, the findings position the organiser as a primordial control system in multicellular organism development, dating back to the dawn of animal evolution itself. It suggests a remarkable evolutionary continuity where the fundamental blueprints for constructing the three-dimensional architecture of multicellular animals remained largely stable across hundreds of millions of years.
The implications of this research extend far beyond ctenophores and sea anemones. Since the organiser guides the spatial coordination of cell fate during development, understanding its origins and conservation sheds light on the evolutionary emergence of animal diversity and complexity. It also offers potential new perspectives for biomedical research, particularly in regenerative medicine and congenital defect studies, where guiding axis formation and tissue patterning is critical.
Technical mastery was central to these findings. The researchers employed advanced microscopy and vital cell staining techniques allowing them to trace transplanted cells dynamically within host embryos. Coupling this with precise microsurgical transplantation provided not only functional but also visual confirmation of organiser activity. This combination of cutting-edge experimental methods enabled insights previously thought unattainable in such fragile and inaccessible embryonic systems.
Prof. Andreas Hejnol reflects on the evolutionary significance with enthusiasm: “Our data demonstrate that this organizer mechanism coordinates the entire body axis and is conserved among one of the earliest-diverging animal lineages, suggesting that complex body plan organisation arose very early in metazoan evolution.” His team’s work bridges developmental biology with evolutionary biology, providing a vivid example of how ancient developmental principles underpin the incredible diversity of life forms on Earth today.
This research, published in the prestigious journal Nature, represents a milestone in understanding early animal evolution and embryogenesis. It dramatically shifts the paradigm surrounding the origins of the organiser and prompts reconsideration of the molecular and cellular processes foundational to animal multicellularity. As scientists continue to explore these ancient mechanisms, further revelations about the building blocks of life’s complexity are eagerly anticipated.
Subject of Research: Animals
Article Title: A blastoporal organiser in a ctenophore
News Publication Date: 17-Jun-2026
Web References: http://dx.doi.org/10.1038/s41586-026-10643-z
Image Credits: Lisa-Marie Barf
Keywords: embryonic development, organiser, blastopore, ctenophore, Mnemiopsis leidyi, evolutionary biology, axis formation, multicellularity, xenotransplantation, sea anemone, cnidaria, developmental genetics
