Hans Spemann - Induction and Organizers

Induction and Organizers

Spemann was appointed Professor of Zoology and Comparative Anatomy at Rostock in 1908 and, in 1914, Associate Director of the Kaiser Wilhelm Institute of Biology at Dahlem, Berlin. Here he undertook the experiments that would make him famous. Drawing upon the recent work of Warren H. Lewis and Ethel Browne Harvey, he turned his skills to the gastrula, grafting a "field" of cells (the Primitive knot) from one embryo onto another.

The experiments, aided by Hilde Proescholdt (later Mangold), a Ph.D. candidate in Spemann's laboratory in Freiburg, took place over several years and were published in full only in 1924. They described an area in the embryo, the portions of which, upon transplantation into a second embryo, organized or "induced" secondary embryonic primordia regardless of location. Spemann called these areas "organiser centres" or "organisers". Later he showed that different parts of the organiser centre produce different parts of the embryo.

Despite his modern reputation, Spemann continued to entertain neo-vitalist "field" analyses similar to those of Driesch, Gurwitsch and Harold Saxton Burr. However, the follow-up work of Johannes Holtfreter, Dorothy M. Needham and Joseph Needham, Conrad Waddington and others showed that organizers killed by boiling, fixing or freezing were also capable of causing induction. The conclusion was that the actual controllers were inert molecules, though little headway was made until the end of the 20th century in discovering how signalling took place.

From 1919 Spemann was Professor of Zoology at the University of Freiburg-im-Breisgau, where he continued his line of enquiry until in 1937 he was relieved of his post to be replaced by one of his first students, Otto Mangold. In 1928 he was the first to perform somatic cell nuclear transfer using amphibian embryos – one of the first moves towards cloning. He was awarded the Nobel Prize in 1935. His theory of embryonic induction by organisers is described in his book Embryonic Development and Induction (1938). He died of heart failure on 12 September 1941. He never lost his love of classical literature and, throughout his life, organized evening gatherings of friends to discuss art, literature, and philosophy.