Ernst Ruska started development of the first electron microscope in 1931 which was the transmission electron microscope (TEM). Source: Internet
However Anawati argues (following Ruska) that the de Anima is a fake by a Spanish author. Source: Internet
History Electron microscope constructed by Ernst Ruska in 1933 Diagram illustrating the phenomena resulting of the interaction of highly energetic electrons with matter. Source: Internet