Conversely, the depletion of microglia in APP/PS1 mice led to no change in amyloid plaque count or size that developed over time, again implying that microglia are unable to effectively phagocytose and degrade amyloid plaques, though the ability of peripheral macrophages to reduce amyloid plaque load was not assessed in this study (49). This evidence concerns the gene APP and amyloidosis.