Regeneration in Echinoderms and Ascidians


The regenerative potential is expressed to a maximum extent in echinoderms and ascidians. They provide unique and valuable deuterostome models, closely related to vertebrates (man included), for an integrated approach exploring regeneration from tissue repair to asexual cloning. The comparison of results derived from different experimental models of echinoderms and ascidians and employing different approaches, in vivo and in vitro, provides an insight on specificity of regulatory mechanisms and processes governing large‐scale pattern formation and information signalling storage between cells and tissues allowing a living system to reliably regenerate and maintain a complex morphology. Since in these animals, regenerative phenomena involve progenitor cells present in the circulating fluids or in the tissues, the crucial questions opened are those related to (1) stemness properties of responsible cells, in terms of origin and derivation (stem cells or dedifferentiated cells) and (2) activities (proliferation and/or migration), plasticity and differentiation potential (derived cellular phenotypes).

Key Concepts:

  • Regeneration is a regulative and conservative developmental process complementary to asexual reproduction.

  • Asexual reproduction (cloning) represents the highest expression of the regenerative potential of an organism.

  • Regeneration processes generally imply the key‐contribution of pluripotential cells (stem cells or reprogrammed cells).

  • Echinoderms utilise regeneration processes at all stages of their life cycle (embryo, larva and adult).

  • Echinoderms can regenerate body parts and even complete individual from a fragment following self‐induced or traumatic amputation processes.

  • In ascidians the potential for asexual development is expressed during colony formation by developing functional individuals from adult tissues.

  • Ascidians are the unique adult chordates able to regenerate completely the ablated nervous system.

Keywords: regeneration potential; asexual reproduction; stem cells; morphogenesis; differentiation; epimorphosis; blastema; arm regeneration; siphon regeneration

Figure 1.

Schematic phylogenetic tree of deuterostome groups.

Figure 2.

Schematic representation of the life cycle of ascidians. Solitary species reproduce only sexually (left), whereas in colonial ascidians both sexual and asexual reproduction are present. Modified from Ballarin and Burighel .

Figure 3.

Echinoderms. Overview of regenerative processes in the crinoid Antedon mediterranea. (a) Drawing of an adult specimen at natural size. The arrows indicate the main structures involved in amputation/regeneration phenomena. See for details in (b) and (d)–(e). Regenerating arms (red rectangle) are also shown. (b) Schematic presentation of the experimental model including arm and explants following autotomy processes. On the left it is shown as the donor arm, on the right the respective arm explants. When reamputated at its distal end, the explant undergoes regenerative processes (in green) in distal direction in parallel to regeneration of its donor arm (in green). (c) Stereomicroscopic view of a regenerating arm (2 weeks post‐amputation). Bar=1 mm. (d) Photographic detail of the aboral appendices (cirri and arrows), frequently subjected to amputation/regeneration. (e) Photographic detail of the lateral branchings of the arms (pinnulae and arrows) which are preferential sites of regeneration. (f) Side view of the central body (calyx), showing the visceral mass (encircled) surrounded by the bases of the arms. (g) Schematic drawing of the internal anatomy showing the visceral mass (in yellow) subjected to evisceration/regeneration. (h) Comprehensive top‐view of the regenerated visceral mass (2 weeks post‐evisceration) photographed at stereomicroscope. The mouth (green arrow) and the anal papilla (blue arrows) are already developed. Bar=2 mm. (i) and (j) Larval stages frequently subjected to regeneration. (i) Swimming larval stage (doliolaria) viewed at scanning electron microscope. Bar=50 μm; (j) sessile larval stage (pentacrinoid) viewed at stereomicroscope. Bar=800 μm. (k) Top‐view detail of the regenerated visceral mass (2 weeks post‐evisceration) at scanning electron microscope. Mouth (green arrow) and anal papilla (blue arrows). Bar=1 mm.

Figure 4.

Echinoderms. Microscopic aspects of arm regeneration in the crinoid Antedon mediterranea. (a)–(c) Schematic reconstruction showing the three main phases of arm regeneration. The arm is shown in sagittal and cross section, with indication about its basic anatomy. (a) repair phase (0–24 h pa); (b) early regenerative phase (24–72 h pa) and (c) advanced regenerative phase (72 h–4 weeks pa). (d)–(j) Regenerating samples seen with different microscopic methods and illustrating the main phases of arm regrowth in experimental conditions (after pseudo‐autotomic amputation). (d) and (g) Repair phase (24 h post‐amputation). Stereomicroscopy (d) overall view of the still flat stump amputation plane (arrows). Bar=240 μm. Scanning electron microscopy (g) gives more details about the wound healing in progress: different migratory cells, fibrous material and tissue debris form a largely incomplete cicatricial layer. Roundish cells can be identified as coelomocytes. Bar=40 μm. (e) and (h) Early regenerative phase (72 hr post‐amputation). Stereomicroscopic view (e) of the arm stump showing a well developed regenerative blastema (encircled). Bar=240 μm. Light microscopic detail (h) of the prominent regenerative blastema. The different coelomic compartments (cc) are developing inside the bud. The bud sagittal section is quite comparable to that shown in (b). Bar=100 μm. Compare with the distal regeneration blastema (1 week post‐amputation) developed by an explant ((i) inset). Bar=100 μm. (f) and (j) Advanced regenerative phase (72 h–3 weeks post‐amputation). Stereomicroscopic views of the stump and the regenerate. The progressive development of the new arm with its internal ossicles (arrows) is evident at different stages: 1 week (f), bar=240 μm; 3 weeks (i), bar=250 μm. (k) Light microscopy detail of the regenerative blastema (72 h post‐amputation). BrdU immunocytochemical protocol (ABC method) for monitoring cell proliferation. Many blastemal cells are strongly labelled (dark nuclei, arrows) as well as the epithelium of the regrowing coelomic canal (arrows), indicating extensive cell proliferation activity. Bar=20 μm. (l)–(o) Regeneration‐competent cells. Trasmission electron micrographs of some of the main migratory cytotypes involved in regeneration. The cells recruited display specific distinctive features. (l) Coelomocyte (presumptive stem cell). Bar=1 μm. (m) Phagocyte with large phagosomes (arrows). Bar=1 μm. (n) Granulocyte with massive number of dense cytoplasmic granules. Bar=3 μm. (o) Dedifferentiating myocyte with evident process of rearrangement/dedifferentiation of their contractile apparatus (arrows). Bar=2 μm. (p) Neural factors involved in crinoid arm regeneration. Substance‐P and TGFβ immunocytochemistry (Texas Red/Sub‐P and FITC/TGFβ double‐fluorescence). Standard arm regeneration (1 week post‐amputaion). Confocal detail of the brachial nerve in sagittal section. The double staining emphasises an highly developed network of neural elements strongly reactive for the two factors: varicose Sub‐P immunoreactive processes (red‐orange) and rectilinear TGFβ immunoreactive processes (green) can be recognised. The amputation plane is on the top. Bar=20 μm.

Figure 5.

Ascidian regeneration and asexual reproduction. (a) On the left, scheme of abdominal region of Clavelina (A) to show the digestive loop with the epicardium (in red), as well as the level of two body section planes (x,y). On the right, following section‐x, a new thorax (with branchia and stigmata) is regenerated exclusively by epicardium (B); after synchronous section‐x and section‐y, bipolar regeneration forms a thorax at the two extremities (C); if section‐y follows section‐x after 72 h, regeneration is unipolar and a complete zooid is regenerated (D) (from Brien, , modified). (b) Schematic illustration of the main modes of budding in ascidians: strobilation (A); stolonic (B); pyloric (C) and peribranchial and vascular (arrow) (D). In red: tissues involved in asexual reproduction (from Nakauchi, , modified).

Figure 6.

Ascidian asexual reproduction. (a) Detail of B. schlosseri colony as visible in vivo. The filtering clonal adults and their buds are embedded in the thin tunic penetrated by a network of defined ‘walled’ vessels (arrows) which terminate in numerous blind peripheral ampullae. (b) Triploblastic vesicular bud. The derivation of the blastozooid organs from the three bud layers is reported (from Brien, ; and Manni and Burighel 2006; modified). (c) Scheme of blastozooids with reference to multipotent cells (red) in representatives of the three suborders. Aplouso‐ and Phlebobranchiata have multipotent cells in epicardium (A, B) and stolonic septum (D). In Stolidobranchiata (C) the atrial epithelium is multipotent (from Kawamura et al., ; modified).



Auger H, Sasakura Y, Joly J‐S and Jeffery WR (2010) Regeneration of oral siphon pigment organs in the ascidian Ciona intestinalis. Developmental Biology doi: 10.1016/j.ydbio.2009.12.040.

Ballarin L and Burighel P (2002) Tunicata and Cephalocordata. In: Knowledge for Sustainable Development – An Insight into the Encyclopedia of Life Support System, Vol. 3. Oxford, UK: UNESCO Publishing/Eolss Publishers.

Bannister R, McGonnell IM, Graham A, Thorndyke MC and Beesley PW (2005) Afuni, a novel transforming growth factor‐beta gene is involved in arm regeneration by the brittle star Amphiura filiformis. Development Genes and Evolution 215: 393–401.

Berrill NJ (1951) Regeneration and budding in tunicates. Biological Review 26: 456–475.

Bertolini F (1932) Rigenerazione dell’ apparato digerente nelle Holothuria. Pubblicazioni della Stazione Zoologica di Napoli 12: 432–444.

Birbaum KD and Sánchez Alvarado A (2008) Slicing across kingdoms: regeneration in plants and animals. Cell 132: 697–710.

Bollner T, Beesley PW and Thorndyke MC (1997) Investigation of the contribution from peripheral GnRH‐like immunoreactive ‘neuroblasts’ to the regenerating central nervous system in the protochordate Ciona intestinalis. Proceedings of the Royal Society of London. Series B 264: 1117–1123.

Brien P (1968) Blastogenesis and morphogenesis. Advances in Morphogenesis 7: 151–203.

Brockes JP and Kumar A (2002) Plasticity and reprogramming of differentiated cells in amphibian regeneration. Nature Reviews. Molecular Cell Biology 3: 566–574.

Brockes JP and Kumar A (2008) Comparative aspects of animal regeneration. Annual Review of Cell and Developmental Biology 24: 525–549.

Brown FD and Swalla BJ (2007) Vasa expression in a colonial ascidian, Botryllus violaceus. Evolution & Development 9: 165–177.

Burighel P and Cloney RA (1997) Urochordata: Ascidiacea. In: Harrison FW and Ruppert EE (eds) Microscopic Anatomy of Invertebrates, Vol. 15. pp. 221–347. New York: Wiley‐Liss, Inc.

Colonna F (1592) Phytobasanos, siue Plantarium aliquot historia in qua describuntur diuersi plantae variores, ac magie facie, viribusque respondentes antiquorum Theophrasti, Dioscoridis, PliniJ, galeni, aliorumque delineationibus, ab alijs hucusque non animaduersae. Fabio Colonna auctore. Accessit etiam piscium aliquot, plantarumque nouarum istoria eodem autore. Nespoli: ex officina Horatij Saluiani. Apud Io. Iacobum Carlinum & Anonium Pacem.

Dahlberg C, Auger H, Sam Dupont S et al. (2009) Refining the Ciona intestinalis model of central nervous system regeneration. PLoS ONE 4(2): e4458. doi:10.1371/journal.pone.0004458.

Daniela Candia Carnevali M (2005) Regenerative response and endocrine disrupters in crinoid Echinoderms: an old experimental model, a new ecotoxicological test. In: Matranga V (ed.) Echinodermata. Progress in Molecular and Subcellular Biology, Vol. 39, Subseries Marine Molecular Biotechnology, pp. 167–198. Heidelberg: Springer.

Daniela Candia Carnevali M (2006) Regeneration in Echinoderms: repair, regrowth, cloning. Invertebrate Survival Journal ( 3: 64–76.

Daniela Candia Carnevali M and Bonasoro F (2001) A microscopic overview of crinoid regeneration. Microscopy Research and Technique 55: 403–426.

Daniela Candia Carnevali M, Bonasoro F, Patruno M and Thorndyke MC (1998) Cellular and moleculkar mechanisms of arm regeneration in crinoid echinoderms: the potential of arm explants. Development Genes and Evolution 208: 421–430.

Daniela Candia Carnevali M, Thorndyke MC and Matranga V (2009) Regenerating echinoderms: a promise to understand stem cells potential. In: Rinkevich B and Matranga V (eds) Stem Cells in Marine Organisms, pp. 245–265. Dordrecht: Springer.

Dendy A (1886) On the regeneration of the visceral mass in Antedon rosaceus. Studies from the Biological Laboratories of the Owens College 1: 299–312.

Eaves AA and Palmer AR (2003) Widespread cloning in echinoderm larvae. Nature 425: 146.

Freeman G (1964) The role of blood cells in the process of asexual reproduction in the tunicate Perophora viridis. Journal of Experimental Zoology 178: 433–456.

Garcia‐Arraras JE, Diaz‐Miranda L, Torres‐Vasquez I et al. (1999) Regeneration of the enteric nervous system in the seacucumber Holothuria glaberrima. Journal of Comparative Neurology 406: 461–475.

Gasparini F, Burighel P, Manni L and Zaniolo G (2008) Vascular regeneration and angiogenic‐like sprouting mechanism in a compound ascidian is similar to vertebrates. Evolution & Development 10: 591–605.

Goss RJ (1992) The evolution of regeneration: adaptive or inherent? Journal of Theoretical Biology 159: 241–260.

Graff JM (1997) Embryonic patterning: to BMP or not to BMP, that is the question. Cell 89: 171–174.

Huet M (1975) Le role du systeme nerveux au cors de la regeneration du bras chez une etoile de mer, Asterina gibbosa (Echinoderme, Asteride). Journal of Embryology and Experimental Morphology 33: 535–552.

Kawamura K, Sugino Y, Sunanaga T and Fujiwara S (2008) Multipotent epithelial cells in the process of regeneration and asexual reproduction in colonial tunicates. Development, Growth & Differentiation 50: 1–11.

Kondo M and Akasaka K (2010) Regeneration in crinoids. Development, Growth & Differentiation 52: 57–68.

Laird DJ, De Tomaso AW and Weissman IL (2005) Stem cells are units of natural selection in a colonial ascidian. Cell 123: 1351–1360.

Lender T and Bouchard‐Madrelle C (1964) Etude expérimentale de la régéneration du complexe neural de Ciona intestinalis (Prochordé). Bulletin de la Société zoologique de France 89: 546–554.

Mackie GO and Burighel P (2005) The nervous system in adult tunicates: current research directions. Canadian Journal of Zoology 83: 151–183.

Morgan TH (1901) Regeneration. New York: Macmillan.

Mortensen T (1921) Studies on the Development and Larval Forms of Echinoderms. Copenhagen: GEC Gad.

Mozzi D, Dolmatov IYu, Bonasoro F and Daniela Candia Carnevali M (2006) Visceral regeneration in the crinoid Antedon mediterranea: basic mechanisms, tissues and cells involved in gut regeneration. Central European Journal of Biology 1(4): 609–635.

Mozzi D, Dolmatov IYu, Ferreri P et al. (2004) Visceral graft and regeneration in the crinoid Antedon mediterranea. In: Heinzeller T and Nebelsick JH (eds) Echinoderms: München, pp. 135–139. Leiden: Balkema.

Nakauchi M (1982) Asexual development of ascidians: its biological significance, diversity, and morphogenesis. American Zoologist 22: 753–763.

Ortiz‐Pineda PA, Ramirez‐Gomez F, Perez‐Ortiz J et al. (2009) Gene expression profiling in intestinal regeneration in the sea cucumber. BMC Genomics 10: 262.

Patruno M, McGonnel I, Graham A et al. (2003) AnBMP2/4 is a new member of the TGF‐B superfamily isolated from a crinoid and involved in regeneration. Proceedings of the Royal Society of London. Series B 270: 1341–1347.

Patruno M, Smertenko A, Daniela Candia Carnevali M et al. (2002) Expression of TGF‐B‐like molecules in normal and regenerating arms of the crinoid Antedon mediterranea: immunocytochemical and biochemical evidence. Proceedings of the Royal Society of London. Series B 269: 1741–1747.

Perrier E (1873) L'anatomie et la régénération des bras de la comatula. Archives of Zoological Experimental Genetics 2: 29–86.

Reichensperger A (1912) Beiträge zur Histologie und zum Verlauf der Regeneration bei Crinoiden. Zeitschrift für Wissenschartliche Zoologie 101: 1–69.

Rinkevich Y, Paz G, Rinkevich B and Reshef R (2007) Systemic bud induction and retinoic acid signaling underlie whole body regeneration in the urochordate Botrylloides leachi. PLoS Biology 5: e71.

Rojas‐Cartagena C, Ortíz‐Pineda P, Ramírez‐Gómez F et al. (2007) Distinct profiles of expressed sequence tags during intestinal regeneration in the sea cucumber Holothuria glaberrima. Physiological Genomics 31: 203–215.

Rosner A, Moiseeva E, Rinkevich Y, Lapidot Z and Rinkevich B (2009) Vasa and the germ line lineage in a colonial urochordate. Developmental Biology 331: 113–128.

Runnström J (1925) Zur Experimentaellen Analyse Der Entwiglung Von Antedon. Wilhelm Roux Archiv fur Entwicklungsmechanik der Organismen 105: 63–113.

Rychel L and Swalla BJ (2009) Regeneration in Hemichordates and Echinoderms. In: Rinkevich B and Matranga V (eds) Stem Cells in Marine Organisms, pp. 245–265. Dordrecht: Springer.

Sabbadin A and Zaniolo G (1979) Sexual differentiation and germ cell transfer in the colonial ascidian Botryllus schlosseri. Journal of Experimental Zoology 207: 289–304.

Sabbadin A, Zaniolo G and Majone F (1975) Determination of polarity and bilateral asimmetry in palleal and vascular buds of the ascidian Botryllus schlosseri. Developmental Biology 46: 79–87.

San Miguel‐Ruiz JE, Maldonado‐Soto AR and Garcia‐Arraras JE (2009) Regeneration of the radial nerve cord in the sea cucumber Holothuria glaberrima. BMC Developmental Biology 9: 3.

Sánchez Alvarado A and Tsonis PA (2006) Bridging the regeneration gap: genetic insights from diverse animal models. Nature Reviews. Genetics 7(11): 873–884.

Satoh N (1994) Developmental Biology of Ascidians. Cambridge: Cambridge University Press.

Schultze LS (1900) Die Regeneration des Ganglions von Ciona intestinalis L. und über das Verhältnis der Regeneration und Knospung zur Keimblätterlehre. Jenaische Zeitschrift für Naturwissenschaft 33: 263–344.

Sea Urchin Genome Sequencing Consortium (2006) The genome of the Sea Urchin Strongylocentrotus purpuratus. Science 314(5801): 941–952.

Sugni M, Wilkie IC, Burighel P and Daniela Candia Carnevali M (2009) New evidence of serotonin involvement in the neurohumoral control of crinoid arm regeneration: effects of parachlorophenylanine and methiothepin. Journal of the Marine Biological Association of the United Kingdom 2: 1–8 doi:10.1017/Soo25315409990531.

Sunanaga T, Watanabe A and Kawamura K (2007) Involvement of vasa homolog in germ line recruitment from coelomic stem cells in budding tunicates. Development Genes and Evolution 217: 1–11.

Thorndyke MC and Daniela Candia Carnevali M (2001) Regeneration neurohormones and growth factors in echinoderms. Canadian Journal of Zoology 79: 1171–1208.

Voskoboynik A, Soen Y, Rinkevich Y et al. (2008) Identification of the endostyle as a stem cell niche in a colonial chordate. Stem Cell 3: 456–464.

Whittaker JR (1975) Siphon regeneration in Ciona. Nature 255: 224–225.

Zeleny C (1903) A study of the rates of regeneration of the arm in the brittlestars Ophioglypha lacertosa. Biological Bulletin 6: 12–17.

Zito F, Costa C, Sciarrino V et al. (2003) Expression of univin, a TGF‐B growth factor, requires ectoderm‐ECM interaction and promotes skeletal growth in the sea urchin embryo. Developmental Biology 246: 217–227.

Further Reading

Ballarin L and Manni L (2009) Stem cells in sexual and asexual reproduction of Botryllus schlosseri (Ascidiacea, Tunicata): an overview. In: Rinkevich B and Matranga V (eds) Stem cells in Marine Organisms. Heidelberg: Springer.

Hyman HL (1955) The Invertebrates: Echinodermata, vol. IV 763pp. New York: McGraw‐Hill.

Odelberg SJ (2004) Unravelling the molecular basis for regenerative cellular plasticity. PLoS Biology 2(8): 1068–1071.

Pearson H (2001) The regeneration gap. Nature 414: 388–390.

Rinkevich B (2002) The colonial urochordate Botryllus schlosseri: from stem cells and natural tissue transplantation to issue in evolutionary ecology. BioEssays 24: 730–740.

Sánchez Alvarado A (2009) Developmental biology: a cellular view of regeneration. Nature 460(7251): 39–40.

Thouveny Y and Tassava RA (1998) Regeneration through phylogenesis. In: Ferretti P and Géraudie J (eds) Cellular and Molecular Basis of Regeneration: From Invertebrates to Humans, pp. 9–43. Chichester: Wiley.

Weissman IL (2000) Stem cells: units of development, units of regeneration and units in evolution. Cell 1000: 157–168.

Contact Editor close
Submit a note to the editor about this article by filling in the form below.

* Required Field

How to Cite close
Carnevali, M Daniela Candia, and Burighel, Paolo(Sep 2010) Regeneration in Echinoderms and Ascidians. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0022102]