| Abstrakt: |
Two reasons might account for the fact that the investigation of brain blood flow is one of the youngest branches of physiological research of circulation. One is that the brain was for many years ethically inaccessible both for surgical treatment and basic research. The second equally important reason is certainly the brain's encasement within the bony skull, which makes its in vivo exposure and observation under physiological conditions difficult. As in other fields of scientific research, mere observation of phenomena formed the beginning. In the 19th century, Donders (1849) described reactions of superficial cerebral vessels in situ. Further systematic observations under in vivo conditions required a certain standard of microscopical technology, which was first applied to the brain by Florey (1925) and described by Forbes, Wolff, and Fog in a series of publications from 1928 onward (Wolff, 1929; Forbes and Wolff, 1928; Wolff and Lennox, 1930; Forbes et al., 1933, 1941; Fog, 1937, 1939a,b; Forbes, 1937a,b, 1938, 1954). Photographic documentation through the microscope provided the only possibility for collection of data. More sophisticated microscopic techniques, such as fluorescence angiography, had to await adequate optic systems and light sources. Heme's (1932) dark ground illuminator and Gottschewki's (1953) high-pressure mercury lamp were important steps in this direction. A high standard of intravital microscopy was subsequently developed by Peters (1955), Zweifach (1954, 1957), Illig (1961), Brånemark and coworkers (Brånemark, 1962, 1965a,b, 1966; Brånemark and Jonsson, 1963; Birch et al., 1968a,b), and others, including the development of kinematography and fluoresence angiography. [ABSTRACT FROM AUTHOR] |
