Scanning electron microscopical studies of the arterial terminals in the red pulp of the rat spleen.

The arterial terminals in the red pulp of the perfused rat spleen were studied by scanning electron microscopy. The arterial terminals were tubular or funnel-shaped and ended openly in the splenic cord. No continuity was observed between the arteries and the sinuses. The endothelial cells of the arterial terminals extended their processes at the fringe of the terminal ends, and these endothelial processes were connected to the processes of the reticular cells of the splenic cord. In addition, large pores, measuring 0.5-8 microns in size, were found in the wall of the terminals adjacent to their end.