blastula: early stage of an embryo produced by cleavage of an ovum; a liquid-filled sphere whose wall is composed of a single layer of cells; during this stage (about eight days after fertilization) implantation in the wall of the uterus occurs
embryo: an animal organism in the early stages of growth and differentiation that in higher forms merge into fetal stages but in lower forms terminate in commencement of larval life
schutzstaffel: special police force in Nazi Germany founded as a personal bodyguard for Adolf Hitler in 1925; the SS administered the concentration camps