embryonal sac

from The Collaborative International Dictionary of English v.0.48

Embryonic \Em`bry*on"ic\, a. (Biol.)
   Of or pertaining to an embryo; embryonal; rudimentary.
   [1913 Webster]

   {Embryonic sac} or {Embryonic vesicle} (Bot.), the vesicle
      within which the embryo is developed in the ovule; --
      sometimes called also {amnios sac}, and {embryonal sac}.
      [1913 Webster]