Historical perspective on neuroembryology: Wilhelm His and his contemporaries.

This year marks the 150th anniversary of the discovery of the neural crest by Wilhelm His (1831-1904). Beyond this discovery, His made possible the program of comparative anatomy at the cellular level thanks to the introduction in 1866 of the first microtome to have micrometer advance. His studies of the origin, migration, and fate of neural crest cells were foundational in the field of neuroembryology and contributed to the establishment of the neuron doctrine. The article places His' work in the scientific context of 19th century embryology, concerned with reconciling the embryonic layers theory, the cell theory and the evolution theory. From a methodological point of view, the article shows that His appears in this context at the junction of two embryological traditions, the descriptive morphological approach and the new experimental approach. The anatomical and physiological exploration of the neural crest and the controversies that followed highlight the transition between these two traditions that His enabled and of which he was one of the initiators.