The striated muscle of hydrozoan medusae:: Development and stability of the differentiated state

In phylogeny, striated muscle cells have evolved the first time in the medusa generation of Cnidaria. Development and histology of this cell type have raised speculations whether or not Cnidaria originate from ancient triploblats. A molecular approach for the identification and expression of genes specifying the mesoderm lineage in true triploblasts will help to answer this question. In difference to the striated muscle cells of other phyla those of medusae exhibit an unparalleled transdifferentiation potential which even includes organ regeneration in vitro. The extracellular matrix controls the stability of the differentiated state of the striated muscle and the initiation of transdifferentiation follows the classical signal transduction from the cell substrate complex through protein kinase C to the nucleus. Many of the typical ECM ligands known from vertebrates were identified in Hydrozoa, however, their role in the control of gene expression needs to be identified in this system.