FIG. 2.

Surface arterioles are organized into a dense reticulum. A. A 150-μm section through the surface arteriolar circulation of striate cortex prepared from a different macaque after removal of surface venules. Clotted red cells are labeled by diaminobenzidine. Although many vessels are filled incompletely, the anastomotic arrangement of the surface arterioles is evident. B. Drawing of the arteriolar reticulum, prepared by using a microscope with a camera lucida attachment. Dots mark the origin of arterioles that penetrate the cortex, located either on the reticulum or its fine terminal branches.