mesoderm

The middle embryonic germ layer, lying between the ectoderm and the endoderm, from which connective tissue, muscle, bone, and the urogenital and circulatory systems develop.

The middle germinal layer of the three-layered embryo of any metazoic animal, lying between the endoderm and the ectoderm.

In botany, the middle layer of tissue in the shell of the spore-case of an urn-moss.

The layer of the blastoderm, between the ectoderm and endoderm; mesoblast. See Illust. of blastoderm and ectoderm.

The middle body layer in some invertebrates.

The middle layer of tissue in some vegetable structures.

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.

the middle germ layer that develops into muscle and bone and cartilage and blood and connective tissue