What are the best methods to study apoptosis?

The best methods to study apoptosis include: 

• Light Microscopy is a fairly reliable and inexpensive method for detecting the various morphological changes that take place during apoptosis. Cell shrinkage and pyknosis can be detected easily by routinely stained light microscopy, particularly during the early stages. 
• Electron Microscopy is a far more effective method of studying apoptosis. It shows more noticeable changes, such as chromatin condensation phase and nuclear material accumulating, under the nuclear membrane. A Scanning Electron Microscope (SEM) or Transmission Electron Microscope (TEM) can be used for this purpose. SEM shows surface changes such as blebbing, smoothening, shrinking or loss of microvillus structures. 
• Single Cell Gel Electrophoresis, also known as the comet assay, is the most precise method of cell death measurement at the single cell level. It has higher sensitivity than other methods and provides more specific information about the extent and heterogeneity of DNA damage. 
• Flow Cytometry is often the preferred technique for the most accurate quantification of apoptosis. In this method, cells are stained with fluorescent dye and passed through a beam of light of a single wavelength. Analyzing the manner in which each cell passing through this beam of light scatters light helps to distinguish apoptotic cells from non-apoptotic cells.