blas·to·derm -.dərm n a blastodisc after completion of cleavage and formation of the blastocoel called also discoblastula
* * *
blas·to·derm (blasґto-dərm) [blasto- + -derm] collectively, the mass of cells produced by cleavage of a zygote, forming the hollow sphere of the blastula, or the cellular cap above a floor of segmented yolk in the discoblastula of telolecithal eggs. Called also germinal membrane, or membrana germinativa. blastodermal, blastodermic adjMedical dictionary. 2011.