The following protocols are for free floating mouse brain sections (see Note 26). Initially, certain controls should be included such as pre-adsorption of the primary antibody with the antigen and omitting of the primary and secondary antibodies as well as the avidin-peroxidase complex. For mouse-on-mouse detection it is appropriate to include omission of the primary antibody in each run. For optimal immunodetection of Aβ plaques it is not necessary to pretreat the sections with heat or formic acid as is needed for human sections. Likewise, for tau staining, pretreatment is not necessary in mouse sections. However, for IAPP staining of the mouse pancreas, epitope unmasking by boiling in citrate buffer is recommended as detailed below.