Mes"o*derm (?), n. [Meso- + Gr. 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.
© Webster 1913.