1) Blastoderm 2) Germinal area 3) Germinal disc 4) Layer 1) Blastoderm 
Type: Term Pronunciation: blas′tō-disk Definitions: 1. The disc of active cytoplasm at the animal pole of a telolecithal egg. 2. The blastoderm, especially in very young stages when it is small.
blastodisc The embryo-forming portion of an egg with discoidal cleavage usually appearing as a small disc on the upper surface of the yolk mass.