An endoscopic vessel harvester includes a vessel keeper for capturing a target vessel within a tunnel that has been dissected along the target vessel. A cutter member cuts and cauterizes side branches while the target vessel is slidably captured in the vessel keeper. A spray nozzle carried by the vessel keeper delivers a preservative fluid via a manual control valve and a conduit. The preservative fluid is sprayed on the target vessel proximate a respective side branch immediately after being cauterized. Thus, a harvested vessel is bathed in preservative fluid prior to being actually removed from the body, enhancing endothelial preservation from cascading events.