Senile Plaques in an Aged Western Lowland Gorilla

Senile plaques (SPs) were found in the cerebral cortex of a 44-year-old Western lowland gorilla (Gorilla gorilla gorilla). All the SPs were obtained as dense assemblies consisting of fibrous materials by silver impregnation, but were not detected by Congo red. More SPs were detected by immunostaining for amyloidb protein (Aβ) and a half of Aβ-positive-SPs were also immunoreactive for apolipoprotein E. Moreover, all SPs were immunoreactive for Aβ 42 and Aβ 43, but not for Aβ 40. SPs also did not contain Aβ 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.