1994 Balzan Prize for Biology (Cell Structure)
René Couteaux (1909 – 1999) began his research more than 50 years ago, before the advent of electron microscopy, and has continued to produce work of the highest excellence and originality, leading the field of neuromuscular and, more generally, synaptic structure. Moreover, he has created an important active school, and he has become the revered mentor of a whole new generation of French neurobiologists. René Couteaux is much admired, not only for his scientific achievements, but as a person of great wisdom and great generosity to his younger colleagues.
Born at Saint-Amand-les-Eaux, France, on 23rd June 1909, René Couteaux, MD., D.Sc, Member of the Institut de France (Académie des Sciences) and of the Academia Europaea, is honorary professor at the Université Pierre et Marie Curie in Paris where he actively carries on research in cellular biology on the nervous system and on skeletal muscles.
After a year spent as Royal Society Visiting Professor at University College London, he was appointed to the Chair of Cytology of the Faculté des Sciences de Paris in 1962 and, in 1967, became director of the Laboratoire de Microscopie électronique appliquée à la Biologie du CNRS.
To refer to some of his important contributions in some detail, beginning with the observation that two very distinct parts can be seen at certain stages in the embryonic development of nerve-muscle junctions: one part includes the terminal branches of the motor axon, the other consists of nucleated sarcoplasm which surrounds these branches. Following this evidence of the discontinuity between motor axon and muscle fibres – at a time when many were still convinced that nervous and muscle elements were continuous René Couteaux made a crucial demonstration. Using a vital stain, Janus Green, he showed that the membrane of the muscle sole-plate is highly differentiated. It presents grooves in which the terminal ramifications of the motor axon lie and numerous lamellae arising from its internal surface. Ultrastructura studies later proved these lamellae were folds of the membrane. He named these structures “the sub-neural apparatus”, known today as “Couteaux’s sub-neural apparatus”.
Having improved, in collaboration with J. Taxi, the histochemical method of Koelle and Friedenwald for detecting cholinesterase, the enzyme which hydrolyses acetylcholine, René Couteaux obtained, with this method, pictures of the sub-neural apparatus identical to those given by Janus Green. This was an observation of major importance for understanding how these synapses work since it showed that the cholinesterase, which inactivates the chemical mediator released by axonal endings after it has excited the postsynaptic membrane, is exactly localized in the sub-neural apparatus.
Further studies on motor ending terminals using the electron microscope, in collaboration with M. Pécot, revealed the presence of parallel bands characterized by a large number of vesicles. These bands, opposite the synaptic folds, were called “active bands” partly because some vesicles were seen to open onto the synaptic cleft, thus providing evidence for the exocytosis phenomenon suggested to account for miniature endplate potentials. Another important observation supporting the vesicular hypothesis of acetylcholine release was the demonstration of “giant” synaptic vesicles in experimental conditions similar to those in which “giant” miniature potentials had been recorded.
The classical studies of René Couteaux on the neuromuscular junction must not conceal other contributions; for instance, those on the junction between muscle fibre extremities and tendinous fibres and his present highly original studies on the regeneration of striated muscle fibres and on the expression of isomyosins, during histogenesis and neo-histogenesis in various types of muscles.
The gratitude and affection felt by many researchers of several generations for “Monsieur Couteaux” are due not so much to the authority with which he exercised important responsibilities in research administration (he was, for example, president of the CNRS Cellular Biology Committee for many years) but to the personal interest he has always shown for the works of others. Generously, he let them benefit not only from his great experience but also from his sharp, critical mi, always governed by balancedjudgement. Many students who worked with him have become eminent biologists themselves, and carry on the study of the nervous system, of the muscles and of nerve-muscle interactions in normal and pathological conditions.