blastoderm /blas″tədurm′/ [Gk, blastos + derma, skin] , the layer of cells forming the wall of the blastocyst in mammals and the blastula in lower animals during the early stages of embryonic development. It is produced by the cleavage of the fertilized ovum and gives rise to the primary germ layers, the ectoderm, mesoderm, and endoderm, from which the embryo and all of its membranes are derived. Also called germinal membrane. Kinds include bilaminar blastoderm, embryonic blastoderm, extraembryonic blastoderm, trilaminar blastoderm. −blastodermal, blastodermic, adj.
