eLife assessment
The ExA-SPIM methodology developed will be important to the field of light sheet microscopy as the new technology provides an impressive field of view making it possible to image the entire expanded mouse brain at cellular and subcellular resolution. The authors provide solid evidence that mostly supports the conclusions. Certain statements were deemed to be overstating the method's capabilities, in particular, the claim of "near isotropic resolution" is not supported by the data as there is a large discrepancy between the x/y and z-resolution. Improved characterization of the new technology and a more expanded discussion of prior work would also be beneficial to the reader.