High-speed, deep, high-resolution multiphoton imaging using expansion microscopy
Microglia, the brain immune cells, monitor their territories using their ramified processes to contribute to the formation and maintenance of neural circuits. A recent study showed that microglial processes have thin filopodia that sense their surroundings with different dynamics from the thicker microglial processes (Bernier et al., 2019). Because it has been assumed that microglia exhibit diversity in gene expression, morphology, and cell density across distinct brain regions (Masuda et al., 2020), there is a growing interest in the correlation of fine morphology with the heterogeneity of microglia. To address this issue, an imaging technology that can capture large-volume images with subcellular resolution is required. This application note introduces an efficient imaging technique that combines a high-speed multiphoton system and expansion microscopy, a recently developed super-resolution microscopy technique.