[Intravital microscopic studies of the pial vessels in the animal experiment]

In cats, a direct observation of the brain surface was made possible by fenestration. The pial vessels were observed by means of intravital incident-light microscopy. Particular attention was paid to blood pressure, blood pH, pCO2 and pO2. Mainly with diffuse vasodilation (hypotension) the capillaries stood out as a close network. Normally, interarterial anastomoses were rarer than intravenous ones. Arteriovenous anastomoses were not found. The interarterial blood column rarely came to a standstill, the intervenously this was observed frequently. Two kinds of intervenous anastomoses were found: short connections between veins running close to each other and long venules between vessels of different outflow systems.