Mesoblast

(tries' -o-blast). In embryology: (a) a large, granular, single cell, the most posterior in each of the two bands from which the mesoderm arises in a metazoan, and which throws off cells to add to the mesodermal band. It appears to be a derivative of the entoderm; (b) The middle layer of the blastoderm, probably derived from both the ectoderm and entoderm, and from which are developed the vascular, muscular, and skeletal systems, the generative glands, and the kidneys. It is also called mesoderm. Kleinenberg protests against the use of the term mesoblast, at least in a sense implying any po ibility of comparison with the primary layers, epiblast and hypoblast, of coelenterata. M., Parietal, M., Somatic, the outer mesoblastic plates entering into the formation of the body-wall. It is also known as Soma top lettre. M.. Splanchnic, M.. Visceral, the inner mesoblastic plates forming the wall of the digestive tract and its derivatives. It known as Splanchnopleme. lesoblastema (mes-o-blas-te' -mah) In embryology. germinal cells that go to form the mesoderm; the mesoblastic cells.