On the cover: Collaterals interconnecting distal branches of the anterior cerebral artery emanating from the mid-saggital sulcus (right) and middle cerebral artery (left) trees reside in the pia of the cerebral cortex (C57BL/6 mouse). Penetrating arterioles descending into the cortex (unfocused) are “end-arteries” that do not interconnect the two pial arterial trees. The vasculature was cleared, dilated, fixed, filled with Microfil, horizontally sectioned at ∼1 mm, and optically cleared, and viewed in intermediate brightfield-darkfield. See related article, page 89.