MESODERM
mesoderm, mesoblast
(noun) the middle germ layer that develops into muscle and bone and cartilage and blood and connective tissue
Source: WordNet® 3.1
Etymology
Noun
mesoderm (plural mesoderms)
(embryology) One of the three tissue layers in the embryo of a metazoan animal. Through embryonic development, it will produce many internal organs of the adult, e.g. muscles, spine and circulatory system.
Coordinate terms
• ectoderm
• endoderm
Source: Wiktionary
Mes"o*derm, n. Etym: [Meso- + Gr. (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.
Source: Webster’s Unabridged Dictionary 1913 Edition