Whole-body protochordate regeneration from totipotent blood cells

B. Rinkevich, Z. Shlemberg, L. Fishelson

Research output: Contribution to journalArticlepeer-review


Cell differentiation, tissue formation, and organogenesis are fundamental patterns during the development of multicellular animals from the dividing cells of fertilized eggs. Hence, the complete morphogenesis of any developing organism of the animal kingdom is based on a complex series of interactions that is always associated with the development of a blastula, a one-layered hollow sphere. Here we document an alternative pathway of differentiation, organogenesis, and morphogenesis occurring in an adult protochordate colonial organism. In this system, any minute fragment of peripheral blood vessel containing a limited number of blood cells isolated from Botrylloides, a colonial sea squirt, has the potential to give rise to a fully functional organism possessing all three embryonic layers. Regeneration probably results from a small number of totipotent stem cells circulating in the blood system. The developmental process starts from disorganized, chaotic masses of blood cells. At first an opaque cell mass is formed. Through intensive cell divisions, a hollow, blastula-like structure results, which may produce a whole organism within a short period of a week. This regenerative power of the protochordates may be compared with some of the characteristics associated with the formation of mammalian embryonal carcinomous bodies. It may also serve as an in vivo model system for studying morphogenesis and differentiation by shedding more light on the controversy of the 'stem cell' vs. the 'differentiation' theories of regeneration and pattern formation.

Original languageEnglish
Pages (from-to)7695-7699
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number17
StatePublished - 15 Aug 1995
Externally publishedYes


  • Botrylloides
  • Tunicata
  • blastogenesis
  • teratomas
  • vascular budding

ASJC Scopus subject areas

  • General


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