The Collaborative International Dictionary of English v.0.48:
blastodisc \blastodisc\ n. a disc-shaped layer of cells on the surface of the yolk mass of an egg (such as that of a bird) which develops to form the embryo. Syn: germinal disc, germinal area. [WordNet 1.5 +PJC]WordNet (r) 3.0 (2006):
blastodisc n 1: a layer of cells on the inside of the blastula [syn: blastoderm, germinal disc, blastodisc, germinal area]