germ layer n any of the three primary layers of cells differentiated in most embryos during and immediately following gastrulation
* * *
any of the three distinct types of tissue found in the very early stages of embryonic development (see ectoderm, endoderm, mesoderm). The germ layers can be traced throughout embryonic development as they differentiate to form the entire range of body tissues.
* * *
germ cell layer any of the three primary layers of cells of the embryo (ectoderm, endoderm, and mesoderm), from which the tissues and organs develop. Called also blastodermic l.Medical dictionary. 2011.