Ultrastructural analysis of the cerebral microvasculature in mice fed low- or high- cholesterol diets. Transversely sectioned capillaries are shown from the entorhinal cortex of C57BL/6J or LDLR-/- mice fed low- (LCD) or high- (HCD) cholesterol diets for 4 months. The microvessel in panel A from a C57BL/6J mouse fed a LCD exhibits a circular lumen, an intact endothelial cell, and smooth capillary walls. Note the altered chromatin structure in the endothelial cell nucleus in panel B, and the swollen endothelial cell nucleus in panel C. A normal endothelial cell nucleus is indicated by an asterisk in A. Arrowheads indicate an expanded extravascular space containing amorphous debris (D), or luminal degeneration (E) in an LDLR-/- mouse fed a LCD (D), or a C57BL/6J mouse fed a HCD (E). Scale bar = 1 μm.