Hans Spemann

Who Imagined the Experiment First · Embryologist · 1869–1941

The embryologist who discovered that one small region of an embryo instructs the rest what to become — and who, in 1938, described the nuclear-transfer experiment that would not be performed on a mammal for another fifty-eight years.

Who was Spemann?

Hans Spemann was born in Stuttgart in 1869 and became professor of zoology at Freiburg. He worked on newt and salamander embryos with instruments he made himself, including a noose of hair taken from his infant son's head — fine enough to constrict an embryo without destroying it. With it he divided an early embryo in two and obtained two complete larvae, showing that the cells had not yet been committed to particular fates. In 1924, with his doctoral student Hilde Mangold, he transplanted a small piece of tissue from the upper lip of the blastopore of one embryo into the flank of another. It induced a second, complete body axis, built largely from the host's own cells. Spemann named that region the organiser, and the discovery won the 1935 Nobel Prize in Physiology or Medicine. Hilde Mangold, who had performed the operation, died in 1924 at twenty-six in a domestic accident and was never included in the award. In his 1938 book Spemann described what he called a 'fantastical experiment': removing the nucleus from a cell that had already differentiated and placing it in an egg whose own nucleus had been taken out, to see whether a whole animal could be built from it. He had no means of attempting it.

Major achievements

• Divided an early newt embryo with a hair noose and obtained two complete larvae
• Discovered embryonic induction and the organiser, with Hilde Mangold (1924)
• Awarded the 1935 Nobel Prize in Physiology or Medicine
• Established experimental embryology as a discipline of transplantation and constriction
• Described the nuclear-transfer experiment in 1938, long before it could be attempted

Life in brief

• 1869 — Born in Stuttgart: Studies medicine, then zoology under Theodor Boveri.
• 1902 — The hair ligature: Splits a newt embryo in two and obtains two complete larvae.
• 1919 — Professor at Freiburg: Where the organiser experiments would be carried out.
• 1924 — The organiser: Hilde Mangold's transplant induces a second body axis.
• 1924 — Hilde Mangold dies: Aged twenty-six, before the work's importance was recognised.
• 1935 — Nobel Prize: For the discovery of the organiser effect in embryonic development.
• 1938 — The fantastical experiment: Proposes moving a differentiated nucleus into an emptied egg.
• 1941 — Dies at Freiburg: Fifty-five years before a mammal was cloned that way.

Explore the life of Spemann — five chapters

1. A Noose of Baby Hair — Making instruments fine enough to ask the question
2. When Does a Cell Decide What It Will Be? — Splitting at different stages, and the answer that emerged
3. Hilde Mangold's Hands — The organiser, 1921 to 1924
4. The Prize She Did Not Share — 1935, and a question about credit
5. The Fantastical Experiment — A sentence written in 1938 that produced a sheep in 1996

Read the five-chapter life of Hans Spemann →

Where Spemann appears in your course

Hans Spemann has a genuine claim on 1 lesson of the Pearson Edexcel International GCSE science course built into Incandio:

• Cloning Mammals — Biology: The procedure on this page was written down in 1938, in a book by a man who had no means of attempting it. Spemann had already shown, using a noose of hair from his infant son's head to constrict a newt embryo, that early cells have not yet been assigned their fates — and with Hilde Mangold he had found the small region of tissue that instructs the rest of an embryo what to become. The obvious next question was whether a cell that had already become something still held the whole instruction set. He proposed moving its nucleus into an emptied egg to find out, and called it fantastical because it was beyond any instrument then existing.

Begin

• Start a conversation with Spemann — a dramatised, historically grounded AI portrayal
• Read the Historical Brief
• Explore the life of Spemann — five chapters
• Find your exam topics · Meet all 208 figures