IDENTIFICATION OF ARTERIAL AND VENOUS SEGMENTS OF BLOOD-VESSELS USINGALKALINE-PHOSPHATASE STAINING OF INK GELATIN INJECTED TISSUES/

The present study describes a method for discriminating between the ar terial and venous segments of blood vessels in mouse tissues and organ s using alkaline phosphatase (ALPase) staining of ink/gelatin injected tissues. Anesthetized mice were injected through the left ventricle w ith blue ink/gelatin, and various organs and tissues were removed from the body and fixed by immersion in 10% formalin. Sections 50-100 mu m thick were incubated for ALPase in a medium containing naphthol AS-BI phosphate and fast red TR by the azocoupling method, In such specimen s as the brain and skeletal muscles, ALPase activity was found in arte rioles and capillaries on the arterial side, whereas it was absent in capillaries on the venous side and in venules. In the liver, only bran ches of the hepatic artery were positive. ALPase activity was absent i n the vessels of the lung except for a positive reaction in branches o f the bronchial arteries. These findings indicate that the ALPase acti vity is confined to the arterioles and arterial segments of the capill aries in the systemic circuit. Thus, ALPase staining of ink/gelatin in jected specimens is a useful method for differentiating the arterial a nd venous segments of the micro-vascular bed in various organs and tis sues in mice.