Hypoblast

from WordNet (r) 3.0 (2006)

hypoblast
    n 1: the inner germ layer that develops into the lining of the
         digestive and respiratory systems [syn: {endoderm},
         {entoderm}, {endoblast}, {entoblast}, {hypoblast}]

from The Collaborative International Dictionary of English v.0.48

Hypoblast \Hy"po*blast\, n. [Pref. hypo- + -blast.] (Biol.)
   The inner or lower layer of the blastoderm; -- called also
   {endoderm}, {entoderm}, and sometimes {hypoderm}. See Illust.
   of {Blastoderm}, {Delamination}, and {Ectoderm}.
   [1913 Webster]