GERM LAYER By N., Sam M.S. - 6 One of three layers of cells in an animal embryo at the gastrula stage that organs and tissues develop. Outermost layer is the ectoderm, middle is mesoderm and is the endoderm. GERM LAYER: "A germ layer is seen in the embryo." Related Psychology Terms ADOLESCENCE (Theories) MESODERM CORTICAL LAYERS Piaget’s Theory of Cognitive Development NEURAL NETWORKS ANIMAL BEHAVIOR CHILD PSYCHIATRY PRENATAL DEVELOPMENT RETINA CIVILIAN CATASTROPHE REACTIONS Cite this page: N., Sam M.S., "GERM LAYER," in PsychologyDictionary.org, May 11, 2013, https://psychologydictionary.org/germ-layer/ (accessed February 2, 2023).