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Thread: Evolutionary relationship between mesoderm & mesoglea?

  1. #1 Evolutionary relationship between mesoderm & mesoglea? 
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    I was reading about invertebrates, and noted that Ctenophores and Cnidarians have a gel-like, acellular layer separating their ecto and gastrodermis, termed the mesoglea. I know these two phyla are diploblastic, and that acoelomorphs, ecdysozoans, lophotrochozans, and deuterostomes (the bilaterians) are all triploblastic, thus they have three primary tissue layers during embryonic development (epi, endo, and mesoderm) as opposed to two. Is it plausible to hypothesize that perhaps the mesodermic layer of the bilaterians evolved from the mesoglea of our diploblastic ancestors? I know the mesoglea functions mainly in support, and read that the mesoderm gives rise to many cell types, including bone and muscle cells. I searched online for any articles examining the evolutionary relationship between the two, but couldn't find anything. I'm kind of new to evolutionary bio, so sorry if this is way off the mark.


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  3. #2  
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    Try google scholar. Here is the search string.

    http://scholar.google.com/scholar?hl...on&btnG=Search

    The first hit looks promising:

    The origin of both mesoderm and muscle are central questions in metazoan evolution. The majority of metazoan phyla are triploblasts, possessing three discrete germ layers. Attention has therefore been focused on two outgroups to triploblasts, Cnidaria and Ctenophora. Modern texts describe these taxa as diploblasts, lacking a mesodermal germ layer. However, some members of Medusozoa, one of two subphyla within Cnidaria, possess tissue independent of either the ectoderm or endoderm referred to as the entocodon. Furthermore, members of both Cnidaria and Ctenophora have been described as possessing striated muscle, a mesodermal derivative. While it is widely accepted that the ancestor of Eumetazoa was diploblastic, homology of the entocodon and mesoderm as well as striated muscle within Eumetazoa has been suggested. This implies a potential triploblastic ancestor of Eumetazoa possessing striated muscle. In the following review, I examine the evidence for homology of both muscle and mesoderm. Current data support a diploblastic ancestor of cnidarians, ctenophores, and triploblasts lacking striated muscle.


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  4. #3  
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    Thank you very much!
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