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SUDIES ON THE RETINA: VIEWED RETRO AND PROSPECTIVELY Tsuneo Tomita 1 1Keio University, pp.13-31
Published Date 1974/1/1
DOI https://doi.org/10.11477/mf.1406203471
  • Abstract
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This is an enlarged version of the lecture de-livered at a gathering in commemoration of the author's retirement from Keio University, held on May 12, 1973, at the International House, Roppongi, Tokyo.

The story begins with his attempt in 1948, three years after the end of World War II, to localizethe ERG components by means of micropipette electrodes inserted into the frog retina. The hard time is recalled, at which the experiment had to be started with substantially no equipment due to the loss of facilities by the war. The earlier ob-servations were reported in the first number of Jap. J. Physiol. (1950) and in three subsequent papers in the same journal and J. Neurophysiol., with the tentative conclusion that the main origin for the components PII and PIII is in the bipolar cell layer, whereas the component PI is of the deepest origin manifesting probably some metabolic interaction between the photoreceptors and pigment epithelial cells. The reports stimulated discussions which lasted as long as fifteen years and which brought about an important outcome that the PIII consists of two subcomponents; the distal PIII which represents the receptor potential, and the proximal PIII which originates in structures in the bipolar cell layer.

The author joyfully recalls his one year of work (1952-1953) at Professor H. K. Hartline's laboratory, Johns Hopkins. During this period, he learned the usefulness of the binocular dissection microscope and the technique of intracellular recording. In addition, he made a number of friends with whom the relation continues as good as ever.

The author's primary interest from the very beginning of his microelectrode study on the verte-brate retina was to record intracellularly the re-sponse of single photoreceptors. Such attempts, however, were never successful until 1964, the year he developed a "jolting" device which propels the tissue into the electrode at very high acceler-ations but with very small displacement. The re-sponse thus obtained from single carp cones was a sustained negative potential and definitely showed Young-Helmholtz's trichromatic type organization. He also observed that vertebrate photoreceptors work entirely differently from most other receptors. Instead of becoming depolarized by the stimulus, they are hyperpolarized. The ionic mechanism was studied with the result that the permeability for Na+ ions is high in the dark and decreased by illumination.

The recent successful application of the intra-cellular recording technique to other retinal cell types has made the analysis of their response possible. The cell identification is made after Kaneko (1970) by Procion Yellow filled electrodes. The author feels that the solution of the essential retinal mechanisms would be attained in a gener-ation. He himself works toward generalization of the observations in the retina to other nerve tissues.


Copyright © 1974, Igaku-Shoin Ltd. All rights reserved.

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電子版ISSN 2185-405X 印刷版ISSN 0006-8969 医学書院

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