Cajal's contributions to glia research.

In 1906, Santiago Ramón y Cajal was awarded the Nobel Prize in Physiology or Medicine in recognition of his work on the structure of neurons and their connections. What is less well known is that he also had a keen interest in glia and developed specific staining methods for their study. In addition to describing their morphology, he speculated on a role for glia in sleep and wakefulness and even in executive brain functions such as attention. In this article, we focus on Cajal's histological research into glial cells; this research includes original drawings of astrocytes, oligodendrocytes, microglia and radial glia, as well as his scientific writings. We aim to show that, concerning glia as well as neurons, Cajal was far ahead of his time.