FIGURE 5.1. Pen-and-ink drawings were the first scientific illustrations to depict the actual structure of individual nerve cells. Several types of neurons are represented here; each has a recognizably thicker portion that is the cell body, and most have a single axon that projects like a thin wire. The number and the branching patterns of each cell 's dendrites show more variation. Source: D. Santiago Ramón y Cajal, 1889. Manuel de Histología Normal y Técnica Micrográphia. The National Library of Medicine.