Visualizing cell behavior has been the goal of many techniques developed in the 20th and 21st century. Cells were initially visualized after removing from the organism after death. However, real-time visualization of cells through fluorescent labeling still proved difficult due to the degree of transparency required to see the fluorescence.
Similarly, imaging techniques have had problems with light scattering. Selective plane illumination microscopy (SPIM) or light-sheet microscopy differs offers high-resolution imaging at various cell depths in live tissues.