Dendritic spines were discovered by Ramón y Cajal in 1888 using the Golgi technique to stain the nervous system. However, for some time, other prestigious scientists considered that dendritic spines were artifacts caused by the Golgi staining technique, and drew neurons with completely smooth surfaces. Ramón y Cajal subsequently confirmed the existence of dendritic spines using a second staining technique, the methylene blue method (pictured here). Dendritic spines are now known to be key components of a variety of microcircuits in the brain, and they are the subject of intense study using super-resolution microscopes where they are found to be highly dynamic structures that might be involved with the cellular basis of learning and memory formation.
A section of rabbit brain was fixed and stained with methylene blue and observed with a light microscope using bright field optics.
Javier DeFelipe, Instituto Cajal (CSIC) and Centro de Tecnología Biomédica (UPM), Madrid, Spain. Image Reproduced with permission of the Cajal Institute, CSIC, Madrid. Spain.