The organizer experiment was a classical experiment in developmental biology carried out by German anatomist, Hans Spemann (1869-1941) and Hilde Mangold (1898-1924) that demonstrated the principle of cell induction.

Spemann and Mangold transplanted a group of cells from one region of an amphibian blastopore (a hollowed out group of rapidly developing cells that occurs soon after fertilization and the onset of early embryonic cell division) to another region of a similar blastopore. The transplanted cells continued along their normal path of development but also induced cells in the new host to change their developmental path.

The transplanted cells developed as they would have on the dorsal side of the original blastopore. The cells invaginated and differentiated into notochord and somites. The transplanted cells induced cells in the new host blastopore to become associated mesodermal structures. The transplanted cells essentially caused the development of a second neural...