Jorge Francisco Tello Muñoz (1880–1958): First Pupil and the Man of Relay of Cajal

The relationship between Tello and Cajal was not easy at the beginning. Cajal believed that Tello had copied in the examination for the prize of his university degree and wanted to exclude Tello from the competition. Fortunately, Dr.Olóriz, Professor of InternalMedicine,whowas alsomember of the tribunal, convinced Cajal that this was impossible because he (Olóriz) had been sitting close to Tello during the whole time of the exam, and besides this, he was very confident on the capacity and honesty of the candidate. Tello, during the studies of the Medicine, worked as an intern in surgery with the famous Professor Ribera, and when he got his M.D. degree, he wanted to become a specialist in surgery. But Tello did not apply on time for the post of medical intern in surgery and, due to financial reasons, he decided to apply for an intern position in the laboratory of histology directed by Cajal, the only internship that was still available. Therefore, Cajal received Tello in his laboratory coldly and mistrustful. Nevertheless, very soon, Cajal completely changed his feeling for Tello. One morning, Cajal arrived at the laboratory and saw, astonished, some cages containing lizards that he had not ordered. Then, he asked to the concierge who answered that the animals had been ordered and paid by Mr. Tello. This agreeably impressed Cajal, who called Tello and asked himwhat hewanted to study in these animals. In his research on these reptiles, Tello discovered giant neurofibrils in the neurons of the spinal cord during winter lethargy. For the histological staining, Tello used the reduced silver nitrate method, recently invented by Cajal. This discovery was the starting point for Tello to further study the effects of physiological winter lethargy in neurons, phenomenon that he finally defined very well. The neurofibrils are protoplasmic organelles that are very sensible to changes in temperature. Due to the action of cold and heat, neurofibrils undergo transient morphologic conglutination and disjoining; in both cases, reversible when temperature backs to control conditions. Cajal himself and several other researchers confirmed these observations posteriorly. Cajal recognized the importance of Tello’s discovery and ordered to publish a “preliminary note” in the second volume of the journal Trabajos del Laboratorio de Investigaciones Biológicas, as well as to publish the complete description later, in the third volume (Tello, 1904a). Then Cajal asked Tello to investigate the structure of the “corpus geniculatum externum” (Fig. 1) and the pupil, under the direction of the master, obtained several original findings (Tello, 1904b). As a result, Tello received the doctorate degree as well as, afterward, the “Extraordinary Prize” (30 June 1903). After the doctoral dissertation, Tello kept on working in Cajal’s laboratory of neurohistology. He investigated the degenerative and regenerative processes in nerve endings (Tello, 1923a, 1942), motor plates, neuromuscular spindles of the skeletal muscles (Tello, 1907a, 1907b), the regenerative processes in the optic tracts (Tello, 1907a, 1907b, 1911a, 1911b), and the influence of neurotropism in the nervous centers (Tello, 1911b; Fig. 2). With his important findings, Tello came in support of Cajal’s “Neurotropic Theory” (Tello, 1911b); not in vain, Dr. Francisco Tello chose the title “Actual ideas about Neurotropism” for his dissertation to be accepted as a member of the Royal National Academy of Medicine (Spain) in 1923 (Tello, 1923b). However, these findings will need more than 50 years to reach the international recognition that undoubtedly deserved and that deserve today. The Uruguayan researcher Alberto Aguayo, Director of Neurosciences researches at the McGill University (Montreal, Canada) reproduced the experiments by Tello in the early 1980s (Vikhansky, 2001), while the Italian Rita Levi Montalcini was awarded the 1986 Nobel Prize in Physiology orMedicine for discovering thefirstmolecule known to stimulate the growth of nerves (NGF)—shared with Stanley Cohen (Vikhansky, 2001).