F1 was from a Lombardy family and was born in 1877. While still a student, he entered the field of research, working under some of the most illustrious names in medicine at that time: Grassi, Sciamanna, Dupré, Pierre Marie, Kraepelin, Nissl, and Alzheimer. In the first phase of his scientific activity, Cerletti concentrated on several issues relating to histology and histopathology and demonstrated how nervous tissue has its own characteristic way of reacting to various pathogenic stimuli. As a consequence of his work, and that of Nissl and Alzheimer, the histopathology of nervous tissue became an autonomous category within the general makeup of the medical sciences. Other important work that Cerletti conducted was on the histopathology of intracerebral vessels, perivascular corpuscles (also known as the corpuscles of Cerletti), the histopathology of neuroglia, the origin of rod cells, the phagocytic processes of cerebral matter, and the pathological alterations of neurofibrils.