Microscopes have played a fundamental role in the development of biology as an experimental science. It was Robert Hooke who, when using a compound microscope in 1655, noticed that thin slices of cork were made up of identical and small self‐contained units, which he called “cells.” The generalization of this observation and its acceptance, though, had to wait until the late 1830s, when German microscopists Matthias Schleiden and Thcodor Schwann—working independently—introduced the “cell theory” of complex organisms. By the second half of the 19th century Magnus Retzius, Santiago Ramo´n y Cajal and Camillo Golgi were busy completing the microscopic anatomical description of the cell.