PSEN1 and Alzheimer disease: In support of our in vivo imaging results, we demonstrate via immunohistochemical staining of post-mortem tissue for 6E10, a common AD marker used to label Aβ, that amyloid plaques on the ipsilateral hemisphere are considerably smaller than plaques found on the contralateral hemisphere following 16 weeks post-implantation in APP/PS1 mice (figure 3(d)).