IN the observations of living animal organs by the ‘intravital microscope’1 it was noticed that cells of some organs of the animal not previously treated with fluorescent dyestuffs contained substances which were excited by ultra-violet light to give a characteristic yellow-green fluorescence. Such substances were chiefly found in the liver cells and in the epithelial cells of the first convoluted tubules of the kidney of all the animals examined, including horses, oxen, dogs, cats, rabbits, guinea pigs, rats, mice, frogs, etc. In the liver two other groups of cells could be found which were fluorescent, but far less strongly; the Kuppfer star-cells, shining with a dull orange-yellow fluorescence, and single cells, showing a reddish fluorescence, near to the blood vessels. The two groups last named have no connexion with the pigments with which this article deals. The intensity of the fluorescence of the epithelial cells of the kidney, and also of the liver cells, appeared to be diminished when the animals (rats) were fed on a diet free from nitrogen, and to be augmented after the administration of urea. The suggestion arose that these pigments might have some connexion with the formation or the excretion of urea, because they were found in great quantity just at the sites of the intensive formation and excretion, and therefore of great concentration, of urea. Since it appeared likely that these pigments had great physiological importance, we tried to isolate and identify them. Animal pigments have been for a long time an object of interest to physiologists and chemists. Especially by the researches of chemists, knowledge of them has been greatly increased during recent decades. The animal pigments hitherto known are nearly all soluble in neutral organic solvents under suitable conditions, and this property was highly important for their isolation and recognition. Only a few of the animal pigments previously known are strongly fluorescent, and their fluorescence differs in colour from that of the pigments now found in the kidney and the liver.
The method of intravital microscopy has been described by Ph. Ellinger and A. Hirt, in the Zeitschrift für Anatomie und Entwicklungsgeschichte, vol. 90, p. 791, 1929 and in Abderhaldens Handbuch der biologischen Arbeitsmethoden.", vol. 5, II2, p. 1753, 1930. It permits living animal organs to be examined with the strongest microscopical magnifications by injecting the animal with fluorescent dyestuffs. With ultra-violet illumination these dyes provide, by fluorescence in the cells themselves, the light required for visible illumination of the microscopical picture.
Bleyer and Callmann, Biochem. Z., 155, 54; 1925.
O. Gerngross and M. Schulz, Milchwirtschaftliche Forschung, 6, 567; 1928.
Details of this procedure as well as of further chemical operations are described in our publications: Ph. Ellinger and W. Koschara, Berichte der Deutschen Chemischen Gesellschaft, 66, 315, 808, 1411; 1933.
We had made an agreement with R. Kuhn, P. Györgyi and Th. Wagner-Jauregg, who worked over the same field and who called their substances Flavins, to call the whole group Lyochromes and their single specimens Flavins, with the addition of the names of the materials of origin, so that the Flavin from milk is called Lacto flavin.
Warburg and Christian, Biochem. Z., 257, 492; 1933.
R. Kuhn, P. Györgyi and Th.—Wagner-Jauregg, Ber. Deutschen Chem. Gesell., 66, 317, 576, 1034, 1577; 1933.
Th. Wagner-Jauregg and H. Ruska, Ber. Deutschen Chem. Gesell., 66, 1298; 1933.
K. G. Stern and G. D. Greville, Naturwissenschaften, 22, 720; 1933.
About this article
Proceedings of the Nutrition Society (1946)
Biological Reviews (1940)
Ergebnisse der Physiologie Biologischen Chemie und Experimentellen Pharmakologie (1939)
Berichte der deutschen chemischen Gesellschaft (A and B Series) (1934)