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Etymology: Gk, organon + izein, to cause
a focal point within the developing embryo from which the organism grows and differentiates. In vertebrates this point is the chorda-mesoderm of the dorsal lip of the blastopore.
1. An embryonic group of cells that induces the development of another structure.
2. A region in an ovum that is responsible for the mode of development of the fertilized ovum.
See also: center