Correlative light-electron microscopy a potent tool for the imaging of rare or unique cellular and tissue events and structures.

In biology, light microscopy (LM) is usually used to study phenomena at a global scale and to look for unique or rare events, and it also provides an opportunity for live imaging, while the forte of electron microscopy (EM) is the high resolution. Observation of living cells under EM is still impossible. Traditionally, LM and EM observations are carried out in different populations of cells/tissues. The advent of true correlative light-electron microscopy (CLEM) has allowed high-resolution imaging by EM of the very same structure observed by LM. This chapter describes imaging with the help of CLEM. The guidelines presented herein enable researchers to analyze structure of organelles and in particular rare events captured by low-resolution imaging of a population or transient events captured by live imaging can now also be studied at high resolution by EM.