Hans Spemann Biography (1869-1941)


The son of a well known book publisher, Spemann was born on June 27, 1869, inStuttgart, Germany. He was the eldest of four children in a family which wassocially and culturally active, and lived in a large home that was well stocked with books (which helped shape the young Spemann's intellect). Upon entering the Eberhard Ludwig Gymnasium, Spemann first wished to study the classics. He later turned to embryology--the branch of biology that focuses on embryos and their development.

He entered the University of Heidelberg in 1891 to study medicine, however, his strict interest in medicine lasted only until he met German biologist andpsychologist Gustav Wolff at the University of Heidelberg. Only a few years older than Spemann, Wolff had begun experiments on the embryological developments of newts and had shown how, if the lens of an embryological newt's eye isremoved, it regenerates. Spemann remained interested and intrigued by both Wolff's finding and also in the newt, on which he based much of his future work. But more than the regeneration phenomenon, Spemann was interested in how the eye develops from the start. He devoted his scientific career to the studyof how embryological cells become specialized and differentiated in the process of forming a complete organism.

Spemann left Heidelberg in the mid-1890s to continue his studies at the University of Munich; he then transferred to the University of Würzberg's Zoological Institute to study under the well-known embryologist Theodor Boveri.Spemann quickly became Boveri's prize student, and completed his doctorate inbotany, zoology, and physics in 1895. Spemann stayed at Würzburg until1908, when he accepted a post as professor at the University of Rostock. During World War I, he served as director of the Kaiser Wilhelm Institute of Biology (now the Max Planck Institute) in Berlin-Dahlem, and following the war, in 1919, he took a professorship at the University of Freiburg.

By the time Spemann began research at the Zoological Institute in Würzburg, he had already developed a keen facility and reputation for conducting well-designed experiments that centered on highly focused questions. His earlyresearch followed Wolff's closely. The eye of a newt is formed when an outgrowth of the brain, called the optic cup, reaches the surface layer of embryonic tissue (the ectoderm). The cells of the ectoderm then form into an eye. Inremoving the tissue over where the eye would form and replacing it with tissue from an entirely different region, Spemann found that the embryo still formed a normal eye, leading him to believe that the optic cup exerted an influence on the cells of the ectoderm, inducing them to form into an eye. To complete this experiment, as well as others, Spemann had to develop a precise experimental technique for operating on objects often less than two millimeters indiameter. In doing so, he is credited with founding the techniques of modernmicrosurgery, which is considered one of his greatest contributions in biology. Some of his methods and instruments are still used by embryologists and neurobiologists today.

In another series of experiments--conducted in the 1920s--Spemann was able toconclude that at a certain stage of development, the future roles of the different parts of the embryo have not been fixed, which supported his experiments with the newt's eye. In an experiment conducted on older eggs, however, Spemann found that the future role of some parts of the embryo had been decided, meaning that somewhere in between, a process he called "determination" musthave taken place to fix the "developmental fate" of the cells.

One of Spemann's greatest contributions to embryology--and the one for whichhe won the 1935 Nobel Prize in physiology or medicine--was his discovery of what he called the "organizer" effect. In experimenting with transplanting tissue, Spemann found that when an area containing an organizer is transplantedinto an undifferentiated host embryo, this transplanted area can induce the host embryo to develop in a certain way, or into an entirely new embryo. Spemann called these transplanted cells organizers, and they include the precursors to the central nervous system. In vertebrates, they are the first cells ina long series of differentiations of which the end product is a fully formedfetus.

Spemann remained at the University of Freiburg until his retirement in the mid-1930s. When not busy with his scientific endeavors, he cultivated his loveof the liberal arts. He died at his home near Freiburg on September 12, 1941.

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