The ciliary rosettes in the gastrodermis may help to remove wastes from the mesoglea, and may also help to adjust the animal's buoyancy by pumping water into or out of the mesoglea.
12.
In contrast to the model based on functional morphology described earlier, in the Epitheliozoa concept the ventral and dorsal cell layers of the Placozoa are homologs of endoderm and ectoderm, the two basic embryonic cell layers of the eumetazoans the digestive " gastrodermis " in the Cnidaria or the gut epithelium in the bilaterally symmetrical Bilateria may have developed from endoderm, whereas ectoderm is, among other things, the precursor to the external skin layer ( epidermis ).
13.
In order to differentiate the use of the word mesenchyme in vertebrate embryology ( that is, undifferentiated tissue found in embryonic true [ ento-] mesoderm from which are derived all connective tissues, blood vessels, blood cells, the lymphatic system, and the heart ) and the use in invertebrate zoology ( a more-or-less solid but looselly organized tissue consisting of a gel matrix [ the mesoglea, in strict sense ] with various cellular and fibrous inclusions, located between epidermis and gastrodermis ), some authors prefer to use the term mesoglea ( in wider sense ) in lieu of mesenchyme when referring to the middle layers of sponges and diploblasts, reserving the term mesenchyme for the embryological sense.
