A multiphoton laser scanning microscope setup for transcranial in vivo brain imaging on mice

We describe a multiphoton laser scanning microscope setup for transcranial in vivo brain imaging in mice. The modular system is based on a modified industrial standard Confocal Scanning Laser Microscope (CSLM) and is assembled mainly from commercially available components. A special multifunctional stage, which is optimized for both laser scanning microscopic observation and preparative animal surgery, has been developed and built. The detection unit includes a highly efficient photomultiplier tube installed in a Peltier-cooled thermal box shielding the detector from changes in room temperature and from distortions caused by external electromagnetic fields. The images are recorded using a 12 - bit analog–to–digital converter. Depending on the characteristics of the staining, individual nerve cells can be imaged down to at least 100 μ m below the intact cranium and down to at least 200 μ m below the opened cranium.