Linear Dichroism of Rods and Cones
Though Boll (1876) was the first to note the bleaching of the reddish colour of the freshly-removed frog retina and Kühne (1878) was the first to extract the light-sensitive coloured substance that he named rhodopsin, it was Schmidt (1938) who introduced a microscopic technique for studying the optical properties of the pigment-bearing cells. Using the polarising microscope, he not only discovered the birefringent and dichroic properties of the frog retinal rod outer segment but accounted for them as well, qualitatively, at least, in terms of the molecular models of cell structure that he proposed. From his observation of dichroism of the rhodopsin-containing rods, he concluded that the pigment molecules must be oriented in the outer segment. Moreover, since transversely polarised light is strongly absorbed by the side-illuminated isolated cells, in the spectral region where rhodopsin absorption is strongest, but not when the light is polarised along the length of the rod, he assigned a transverse orientation to the rhodopsin molecules within the rod cells.
KeywordsOuter Segment Visual Pigment Specific Density Linear Dichroism Dichroic Ratio
Unable to display preview. Download preview PDF.
- Boll, F. (1876). Zur Anatomie und Physiologie der Retina. Monatsber. Kön. Preus. Akad. Wissensch. Berlin. Nov. 783–788.Google Scholar
- Harosi, F.I. (1971). Frog rhodopsin in situ: orientational and spectral changes in the chromophores of isolated retinal rod cells. Ph.D. Thesis. The Johns Hopkins University, Baltimore, Md.Google Scholar
- Harosi, F.I. (1974). Absorption Spectra and linear dichroism of some amphibian photoreceptors. (In preparation).Google Scholar
- Harosi, F.I. and F.E. Malerba (1974). Plane-polarised light in microspectrophotometry. Vision Res. 14 (in press).Google Scholar
- Kühne, W. (1878). On the photochemistry of the retina and on visual purple, edited by M. Foster. Macmillan, London.Google Scholar
- Marks, W.B. (1963). Difference spectra of the visual pigments in single goldfish cones. Ph.D. Thesis. The Johns Hopkins University, Baltimore, Md.Google Scholar
- Oster, G. (1955). Birefringence and Dichroism. In: Physical Techniques in Biological Research. Vol. I. Optical Techniques. Chapter 8, pp. 439–460, edited by G. Oster and A.W. Pollister, Academic Press, New York.Google Scholar
- Svaetichin, G., K. Negishi, and R. Fatehchand (1965). Cellular mechanisms of a Young-Hering visual system. In: Ciba Foundation Symposium on Colour Vision: Physiology and Experimental Psychology, p. 178–207, edited by A.V.S. DeReuck and J. Knight, Little, Brown, Boston.Google Scholar