The fluorescent property of the subretinal tapetum of various mammals was first reported by Hosoya in 1929.1 Recent investigations on the composition of this tissue have revealed the presence of zinc cysteinate in high concentrations in the tapeta of carnivores2,3 and the occurrence of crystals of riboflavin in the tapetum of the lemur.4 We recently observed the striking fluorescence of the tapetum lucidum cellulosum of the cat and undertook the identification of the substance responsible for this fluorescence in an attempt to gain some understanding of its role, if any, in vision.
Material and Methods
Spectral grade butanol essentially free from fluorescent impurities was obtained from Fisher Scientific Company. Riboflavin, flavin mononucleotide (FMN), and flavin adenine dinucleotide (FAD) were products of the Sigma Chemical Company.Ascending paper chromatography on strips of Whatman No. 1 chromatography paper was carried out with the following solvent mixtures5: A, butanol: