noun. undefined

noun. In embryology: A hollow sphere (vesicular morula) composed of a single layer of blastomeres or derivative cells, inclosing a central cavity or blastocœle.

noun. By Haeckel restricted to the germ-vesicle, vesicular embryo, or blastodermic vesicle of the Mammalia, which follows after gastrulation, and is called by him a gastrocystis, or intestinal germ-vesicle. Also called blastula.

noun. The hollow globe or sphere formed by the arrangement of the blastomeres on the periphery of an impregnated ovum.

noun. A blastula

noun. 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

"At first the cells present the appearance of a bunch of grapes or the grains of a mulberry, the morula stage; the growth proceeds rapidly, a cavity forms itself inside and the blastosphere stage is reached."

conceptus  embryo  fertilized egg  

blastocyst  blastodermic vessicle