MESODERM

Mes″o‐derm (?), n. [[Meso- + Gr. δέρμα skin.]] (Biol.) (a) The layer of the blastoderm, between the ectoderm and endoderm; mesoblast. See Illust. of Blastoderm and Ectoderm. (b) The middle body layer in some invertebrates. (c) The middle layer of tissue in some vegetable structures.