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Having body tissues derived from three germ layers, the endoderm, mesoderm, and ectoderm, seen in all multicellular animals except certain invertebrates such as the cnidarians and sponges.

[Greek triploos, triple; see pel- in Indo-European roots + -blastic.]

trip′lo·blas′ty n.


(Zoology) (of all multicellular animals except coelenterates) having a body developed from all three germ layers. Compare diploblastic
[C19: from triplo- threefold (from Greek triploos) + -blast]


(ˌtrɪp loʊˈblæs tɪk)

(of an embryo) differentiating into three primary layers, the ectoderm, endoderm, and mesoderm.
[1885–90; < Greek tripló(os) threefold + blastikós budding]
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References in periodicals archive ?
Triploblastic relationships with emphasis on the acoelomates and the position of Gnathostomulida.
Triploblastic relationships with emphasis on the acoelomates and the position of gnathostomulida, cycliophora, plathelminthes, and chaetognatha: a combined approach of 18s rDNA sequences and morphology.
were examined by transmission electron microscopy and found to be of a triploblastic metazoan, most probably a polychaete (Todt & Salvini-Plawen 2005).
Despite being trained in comparative anatomy, or perhaps because of it, I was distrustful of some of the morphological criteria - for example, diploblastic versus triploblastic, or proterostome versus deuterostome - used in reconstructing phylogeny.
They have a primitive morphology with simple triploblastic bodies (based on body-plan categories).
Whether the cleavages are spiral or not, a major aspect of the evolution of diploblastic into triploblastic Metazoa is the formation of a third germ layer, the mesoderm.
Now that many of the components of innate immunity have been identified in cnidarians, we can begin to assess whether they are performing a role homologous to the role in triploblastic animals.