Spherulites in human brain tissue are composed of β sheets of amyloid and resemble senile plaques.

Recent evidence showed that amyloid-β, Aβ(42), formed spherulites in vitro and, possibly, in vivo in Alzheimer's disease brain tissue. We now confirm the presence of spherulites in human brains and that they are composed of β sheets of amyloid. The spherulites were identical in appearance to spherulites of Aβ(42) formed in vitro which suggested that they may too be composed of Aβ. The physiological significance of this finding may be in its support of previous speculation that spherulites in human brain tissue are the 3-dimensional manifestations of what are otherwise identified as senile or neuritic plaques.