Senile plaques in an aged Western lowland gorilla

Senile plaques (SPs) were found in the cerebral cortex of a 44-year-old Wes tern lowland gorilla (Gorilla gorilla gorilla). All the SPs were obtained a s dense assemblies consisting of fibrous materials by silver impregnation, but were not detected by Congo red. More SPs were detected by immunostainin g for amyloid beta protein (API and a half of A beta -positive-SPs were als o immunoreactive for apolipoprotein E. Moreover, all SPs were immunoreactiv e for A beta 42 and A beta 43, but not for A beta 40. SPs also did not cont ain AP precursor protein-positive structures, These findings suggested that SPs in this case were diffuse plaques. To our knowledge, this is the first report of SPs in the gorilla.