Cajal´s achievements in the field of the development of dendritic arbors

13 páginas, 7 figuras.In 1909, Cajal published an up-dated version in French (Cajal, 1909-1911) of his main work Texture of the Nervous System of Man and Vertebrates (Cajal, 1899-1904), considered the most important book devoted to the nervous system. Owing that last year was the centenary of this publication, we decided to produce an article focused on Cajal´s description of the morphological changes that dendritic trees undergo during development. We will emphasize his brilliant hypotheses explaining the modelling of dendritic trees (the neurotropic hypothesis and the role of neuronal activity in the patterning of the dendritic trees), and the status of this topic in present day Neuroscience. Here, we will show original photographs taken from a selected collection of Cajal´s slides housed in the Cajal Museum (Instituto Cajal, CSIC, Madrid, Spain) illustrating the principal changes in neuronal morphology at different stages of development of the spinal cord, cerebellum and cerebral cortex. We will also discuss Cajal’s initial proposals regarding the influence of neurotropic substances (chemotactic hypothesis) and neural activity in the modelling of the dendritic tree, as well as the evidence that later confirmed these theories.P. GL. is supported by the Fundación Caixa Galicia. This study was supported by grants from Spain´s Ministry of Science and Innovation (SAF2007- 60010) and the Instituto de Salud Carlos III (RETICS, RENEVAS, RD06/ 0026/1001).Peer reviewe