Short answers, pulled from the story.
Cajal demonstrated that neurons are not a continuous network but separate cells with gaps between them, providing definitive evidence for the neuron theory. He also discovered the axonal growth cone and identified dendritic spines on nerve cells.
Cajal received the Nobel Prize in Physiology or Medicine in 1906, shared with the Italian scientist Camillo Golgi. The prize was awarded in recognition of their work on the structure of the nervous system.
The interstitial cell of Cajal (ICC) is a cell type Cajal discovered while mapping neural structures. These cells are found among neurons in the smooth muscles of the gut, where they generate and pace the slow waves of contraction that move material along the gastrointestinal tract.
Cajal's drawings of brain cell structure, made using an improved version of Golgi's staining method, captured neuroanatomical detail with a clarity that photographs of his era could not match. Hundreds of his illustrations have been in use for educational and training purposes since the mid-20th century.
Cajal stated in 1894 before the Royal Society of London that the ability of neurons to grow in an adult and their power to create new connections can explain learning. That statement is now considered the origin of the synaptic theory of memory.
Cajal was born on the 1st of May 1852 in Petilla de Aragón, Navarre, Spain. He died in Madrid on the 17th of October 1934, at the age of 82.