  Previous simulation studies by Menzel et al. [Phys. Rev. X 10, 021002 (2020)]
have shown that scattering patterns of light transmitted through artificial
nerve fiber constellations contain valuable information about the tissue
substructure such as the individual fiber orientations in regions with crossing
nerve fibers. Here, we present a method that measures these scattering patterns
in monkey and human brain tissue using coherent Fourier scatterometry with
normally incident light. By transmitting a non-focused laser beam (wavelength
of 633 nm) through unstained histological brain sections, we measure the
scattering patterns for small tissue regions (with diameters of 0.1-1 mm), and
show that they are in accordance with the simulated scattering patterns. We
reveal the individual fiber orientations for up to three crossing nerve fiber
bundles, with crossing angles down to 25{\deg}.
