Source : Webster's Revised Unabridged Dictionary (1913)

Blastema \Blas*te"ma\, n.; pl. {Blastemata}. [Gr. ? bud,
   sprout.] (Biol.)
   The structureless, protoplasmic tissue of the embryo; the
   primitive basis of an organ yet unformed, from which it
   grows.

Source : WordNet®

blastema
     n : a mass of undifferentiated cells from which an organ or body
         part develops
     [also: {blastemata} (pl)]