Confocal imaging
    Sections were imaged row-wise on a confocal imaging dish (series GWSt-5030, WillCo Wells, Amsterdam) with a spinning disk confocal (Ultraview VoX, Perkin-Elmer) fitted with an electron multiplier CCD camera (9100-02, Hamamatsu Photonics) using an inverted microscope (DMI6000, Leica).  Congo Red was excited with a 561nm laser, and emitted light was then filtered with an emission wheel allowing 525nm (width = 50) and 640nm (width = 120) wavelengths.  Alexa Flour™ 488 secondary antibodies were excited with 488nm laser, and emitted light filtered with an emission wheel allowing 527nm (width = 55). Laser powers were adjusted section-wise to minimize background fluorescence and maximize contrast.  Z-stacks were captured from the center 20µm of each 40µm section using Volocity software (Improvision, Perkin-Elmer).