\Mes`o*the"li*um\, n. [NL., fr. Gr. me`sos middle +
E. epithelium.] (Biol.)
Epithelial mesoderm; a layer of cuboidal epithelium cells,
formed from a portion of the mesoderm during the
differetiation of the germ layers. It constitutes the
boundary of the c[oe]lum.