In this paper, my aim is to understand the origin of experimental and scientific models of pathogeny of the diseases of the nervous system in the Salpêtrière (Paris). I will analyse the role of the contexts of cell theory, microscopy and the advances in histological techniques in the creation of various pathogenic models, based on the concept of the cell, the Wallerian degeneration and the neurone concept. I argue that, as medicine and pathology remain autonomous in their methods and goals, (...) because of the evident degree of complexity of diseases, close and reciprocal interactions with sciences, their practices and theories, make it possible to establish convergences between clinical observations, pathological data and those from the experimental models of pathologies. The search for pathogenic models behaves like an engine, which is efficient in assembling facts, in testing pathogeneses and reforming nosologies, combined with the breakthroughs in biology. This paper is a case study showing the emergence of such interactions in the last decades of the nineteenth-century in Paris. (shrink)