Observation of microglia in vivo using three-photon fluorescence microscopy

Microglia, as important immune cells in the central nervous system (CNS), are closely related to human health and the occurrence and development of various CNS diseases. However, in animal models, due to the lack of deep imaging technology, the research on these cells has been limited to the brain surface. Here, we break this depth limitation by using a self-built 1700nm band three-photon microscopy system, combined with genetically encoded fluorescent markers for brain injection, to achieve deep imaging of microglia in the brain of living animals. We also characterized the three-photon properties through an in vivo multi-photon emission spectrum measurement system at the 1700nm band. This technology enables the visualization of microglia in the white matter layer and real-time detection.