With their illustration works, these women who shared space and time with Cajal, or with one of his disciples, participated in the neuroscientific production of the Spanish Neurological School, as shown in two works, published in 2019 and in 2021 in the magazine Frontiers. in Neuroanatomy [1][2].

If there were illustrators in the Cajal School, it is because scientific illustration was and is an essential pillar of science communication. In the words of Elena Giné, one of the authors of these two works: “Cajal and some of his disciples, such as his brother Pedro, Domingo Sánchez, Achúcarro, del Río-Hortega, De Castro and Lorente de Nó, were authentic masters of illustration of his observations”, but not Francisco Tello (Horse of Pentacles of the neurodeck), who needed technical help to make his illustrations. Although we have only been able to rescue the full name of two illustrators, Conchita del Valle and Mª G. Amador, because they sign 84 and 71 drawings, respectively, there are another 141 illustrations with an unidentified acronym (ERNA) and 247 more unsigned, which It gives an idea of the volume of work that would have been carried out, almost entirely, by women.

Just as words from one language are translated into another taking into account who they are addressed to, the illustrator also “translates” complex scientific topics, processes or objects into visual language in a precise, clear and objective way so that the audience to whom they can understand them can understand them. their creations are destined. As in translation, also the first step of scientific illustration is to investigate thoroughly [3] to know perfectly what is going to be illustrated, because you can only draw what you understand.

The illustrators of the Cajal School were experts in capturing reality as it was seen under the microscope. They had a great ability to extract the maximum number of details from the preparations to incorporate them into their illustrations, and to do so they had to have solid knowledge of the anatomy of the nervous system and a good understanding of the physiological processes they support. Thus they were able to make illustrations at the level of the quality of the scientific works of Cajal and his disciples. Proof of this is that Conchita del Valle collaborated with Fernando de Castro in the illustrations of his work on the carotid sinus, despite the fact that this disciple of Cajal was an excellent draftsman.

Since their origins, scientific illustrations have been the indispensable complement to research work, with scientists themselves as the first promoters of the discipline, both for educational purposes and to publicize the results of their research. Currently, they are also essential tools within dissemination strategies that seek to bring science closer to the general public.
Until the end of the 19th century and the beginning of the 20th century, drawings facilitated the internationalization of scientific work, because they allowed knowledge to be communicated without the need for supporting texts that frequently had to be translated into French or German, because English was not yet the language of The science.

“Good drawing, like good microscopic preparation, are pieces of reality, scientific documents that retain their value indefinitely and whose revision will always be profitable, whatever the interpretations to which they have given rise.” Ramon y Cajal [4]

Always concerned with representing reality in the purest and most objective way, Cajal used his extraordinary artistic gifts to represent in two dimensions the three-dimensional structures that he saw under the microscope. He was also helped by his deep knowledge of photography, another field that he explored in search of the best techniques to “capture reality as it is.” His disciple Fernando de Castro Rodríguez [5] says that “During the years 1917-18, Cajal devised photography that he called biplanar and multiplanar […] with the desire to be able to achieve […] the three-dimensional impression of neurons “, similar to a forest, during the projection of the slide consisting of a set of two or three photographs that had previously been obtained of the same subject.” With such a photographic procedure it seems that he achieved “beautiful three-dimensional images” of the nervous tissue and the networks of the injected blood capillaries.

Although photomicrography began to be used in Cajal’s laboratory in the early 1920s, it could not compete with the quality and quantity of information provided by drawings of tissue preparations. At that time, the techniques for staining cells gave a very opaque, almost black background, which made it very difficult to take easy-to-interpret photographs. This is how hand drawing became the perfect complement to the Golgi method and other histological techniques at the dawn of Neuroscience [1], while photographic chemistry was of great help to make this staining technique more reliable, with which Cajal demonstrated the individuality of nerve cells. All of this knowledge that he collected, duly illustrated, in his Manual of normal histology and micrographic technique, published in 1899 and in his book Photography of colors. Scientific bases and practical rules, published in 1912.

Although “illustration does not seek the magical, unique and unrepeatable moment [of the artist]”, but rather “the absolute data, valid forever, universal and repeatable” because its objective “is the schematic and detached exposition of data on morphology, the life and customs of the subjects represented” [14], it is impossible not to appreciate the beauty of the illustrations signed by Santiago Ramón y Cajal. In them, scientific precision combines wonderfully with artistic delicacy to achieve genius: connecting the shape of nervous structures with their function. And this beauty has allowed Cajal’s drawings to cross the borders of science to tour art museums, filling the pages of books like The Beautiful Brain. The Drawings of Santiago Ramón y Cajal (2017) or inspire artistic currents, such as the surrealism of which Lorca and Dalí were champions [7][8].
Fernando de Castro Rodríguez, a prominent disciple of Cajal, already predicted in 1966 [9] that one day Cajal’s drawings would be considered works of art, even regardless of their scientific value.

«Cajal’s histological drawings… We cannot continue without stopping for a moment at this point, where we could say that here Science becomes Art. His drawings of the nervous system are famous throughout the world. With incomparable skill he faithfully reproduces all the grace and subtlety of the beautiful forms of neurons, and even manages to achieve in a composition – without resorting to the simplicity of the scheme – that we see synthetically reflected the very complex warp of a place or structural nucleus of the brain. medullary. I am convinced that if an exhibition of Cajal’s histological drawings were ever held, they would produce astonishment among the artists and fans of painting and graphics of our time. Leonardo Da Vinci, an exceptional anatomical draftsman, as we know, would surely have been enthused by Cajal’s exotic drawings. Fernando de Castro Rodríguez, 1966.

Currently, the scientific illustrator Román García Mora [10] sees it as more appropriate to speak of “scientific visualization” to encompass the wide range of graphic representation techniques that go beyond traditional illustration. Although today drawing and photography continue to complement each other [11], new technologies and digital support enhance and expand the possibilities of visual communication of science with new formats:  infographics, models, three-dimensional digital models, virtual reality, dioramas, applications of software, etc. [4][12]. Nor do advances in immunohistochemistry and immunocytochemistry techniques (working with conjugated antibodies and fluorochromes) combined with new microscopy techniques (fluorescence, confocal, multiphoton) compete with classical illustration, but rather complement it.

Scientific illustration continues and will continue to be the basis of future scientific communication because it fulfills essential functions that are its own, such as [13]:

• the possibility of emphasizing the most significant scientific information,
• highlight details that would otherwise go unnoticed,
• displace scientifically irrelevant elements into the background, or
• make simplifications that facilitate our understanding of complex processes or structures.

Good proof of this is that books with illustrations by Santiago Ramón y Cajal continue to be, in the 20th century, an essential reference for neuroscience.