Louisa Gross Horwitz Prize, 1983 : Viktor Hamburger: introduction

by John G. Hildebrand


This evening we honor three extraordinary scientists for their studies and discoveries that have helped us understand what controls the development of cells and tissues in embryonic animals. As will become evident, the research endeavors and, indeed, the lives of Viktor Hamburger, Rita Levi-Montalcini, and Stanley Cohen have intertwined in significant and sometimes very special ways.

This happy story begins more than 60 years ago when the time came for Viktor Hamburger to begin his graduate studies. Already fascinated by animal development, he decided to join the laboratory of Hans Spemann in Freiburg. As a graduate student there, Hamburger worked not only in close association with the leading experimental embryologists in Europe at that time, but also in frequent contact with Ross Harrison, the greatest of American embryologists, who regularly visited Spemann's department during the summers. Reflecting on his student years, Viktor Hamburger has written:
"To have two mentors of such stature is indeed a rare gift for a budding experimentalist."
"I soon found out that the developing nervous system is an ideal playground for the study of a variety of intricate embryonic relationships."

In Freiburg Hamburger mastered the elegant experimental approach of his teachers and focused on the developing nervous system for his research. His doctoral thesis, which was published in 1925, has to do with limb growth and led him, indirectly, to a critical test of the role of innervation in the development of limbs in frog embryos. As a postdoctoral research student in Dahlem, he showed clearly that denervated limbs develop quite normally. This work, which was published in 1927 and 1928, marked the crystallization of Viktor Hamburger's lifelong interest in the mutual interactions and influences of limbs and their spinal motor innervation during embryonic development.

Shortly after that, in 1932, a pivotal event in his life took place. Hamburger received a Rockefeller Travelling Fellowship to work in F. R. Lillie's laboratory at the University of Chicago. There he became acquainted with a different experimental preparation -- the chick embryo -- to which he brought the powerful techniques he had mastered in Freiburg. As it turns out, Viktor Hamburger has had a lot to do with making the chick embryo one of the most important research systems in experimental embryology.

When he arrived in Chicago, he intended to stay for only one year. But the Nazi party's rise to power in Germany in early 1933 changed those plans. As a consequence, his stay in Chicago stretched into 1935. In that year, he was appointed Assistant Professor of Zoology at Washington University in St. Louis, where he has remained for the last 48 years, 25 of them as chairman of his department.

Most investigators consider themselves lucky to take part in just one or two important developments in their field of science. In his long career, Viktor Hamburger has been associated with essentially all of the major advances in his field. Regrettably, there is far too much to describe here even cursorily. But I must mention two especially important avenues of research in which he has made key contributions.

One influential line of his research -- provocative at first and now extremely important for contemporary thinking in developmental neurobiology -- has been his exploration and appreciation of the role of nerve-cell death in the sculpturing of the central nervous system during normal embryonic development. A second important line of research has been his investigation of the mechanisms underlying the interactions between developing nerve cells and their targets, such as, muscle cells or other nerve cells.

Hamburger's progress and contributions on both these research paths benefitted from what has been described as one of those lucky accidents that favor the prepared, persistent, and deserving mind.

Shortly after World War II, Hamburger chanced upon three resaerch papers that had been published during the War years in relatively obscure journals by Rita Levi-Montalcini and her mentor, Guiseppe Levi. Stimulated by a key paper Hamburger had published in 1934, their research probed the effects of limb ablation on developing spinal ganglia. Although their studies largely confirmed Hamburger's earlier experimental findings, their interpretation and conclusions were different from his. Viktor Hamburger's response to this potentially troublesome disagreement was profoundly important for the later evolution of the field. He was apparently neither chagrined over the difference of interpretation nor inclined to dismiss it because of its relative obscurity. With characteristic forthrightness he contacted Dr. Levi-Montalcini and persuaded her to come to St. Louis to reexamine the problem in his laboratory. So began one of the most fruitful collaborations in neuroembryology. And it proved to be a lasting one, for like Hamburger's "brief" visit to the United States 15 years earlier, Dr. Levi-Montalcini remained at Washington University until her retirement some 30 years later.

Their collaboration was indeed productive. Their discovery, in 1949, that normally occurring cell death in spinal ganglia is modulated by peripheral targets, forms a foundation for our present views about competitive processes in the development of the nervous system. And central to this evening's Louisa Gross Horwitz Prize Award was their discovery of a diffusible agent that was produced by certain tumors and promoted the growth of nerve cells. Later, through collaboration with Stanley Cohen, this agent was shown to be a protein. They named it Nerve Growth Factor, and it has become the prototypic "trophic substance" in developmental biology.

Viktor Hamburger's long love affair with experimental neuroembryology has continued apace to this day. His skillful hands, sharp and critical eyes, and penetrating and logical mind have made him one of the most influential contributors to the science of developmental biology. No less important, his imagination, insight, and characteristic fairness and generosity have inspired countless students and colleagues. Tonight, as we acclaim the substance of Viktor Hamburger's research, so we celebrate his humanity and the way he has worked.

©John G. Hildebrand
[Transcribed from typescript by Ruth Lewis, October 3, 2000, with permission from John G. Hildebrand.]