The Collaborative International Dictionary of English v.0.48:

Germinal \Ger"mi*nal\, a. [See Germ.]
   1. Pertaining or belonging to a germ; as, the germinal
      vesicle.
      [1913 Webster]

   2. (Biol.) Of or pertaining to the germ, or germ cells, as
      distinguished from the somatic cells.
      [Webster 1913 Suppl.]

   Germinal layers (Biol.), the two layers of cells, the
      ectoblast and entoblast, which form respectively the outer
      covering and inner wall of the gastrula. A third layer of
      cells, the mesoblast, which is formed later and lies
      between these two, is sometimes included.

   Germinal membrane. (Biol.) Same as Blastoderm.

   Germinal spot (Biol.), the nucleolus of the ovum.

   Germinal vesicle, (Biol.), the nucleus of the ovum of
      animals.
      [1913 Webster]