DOCSLIB.ORG

Both Rod and Cone Disc Shedding Ore Related to Light Onset in the Cat

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Both Rod and Cone Disc Shedding Ore Related to Light Onset in the Cat Both Rod and Cone Disc Shedding ore Related to Light Onset in the Cat Sreven K. Fisher,* Bruce A. Pfeffer.f and Don H. Anderson* Nineteen domestic cats were entrained to a 12-hr light/12-hr dark lighting cycle and killed at different times of the cycle. The numbers of rod and cone phagosomes in the retinal pigment epithelium (RPE) were quantified by light microscopy. The number of both rod and cone phagosomes shows a large increase within 2 hrs after light onset. Thereafter, the phagosome count remains low until the latter part of the dark period when the number of rod and cone phagosomes increases slightly. In a few cases, substantial variability in phagosome numbers was found between animals killed at the same times in the lighting cycle. Small (0.4-0.8 Mm), dense, membrane-bound granules, that have the ultrastructural features of lysosomes, occur in large numbers in the tapetal RPE cells. The granules may contain only a homogeneous matrix or matrix plus membrane fragments or melanin. Variations in the number of such granules in different animals shows no clear diurnal pattern. Phagosome number, size, and length measurements of outer segments are used to provide estimates of cone outer segment turnover time in the cat. Invest Ophthalmol Vis Sci 24:844-856, 1983 In a wide variety of vertebrate species, rod outer within the processes of the cone sheath for some time segments shed discs in response to light onset or at before reaching the RPE cell bodies.1213 In the cat the beginning of the light part of the daily light-dark retina, our results clearly show that both rods and cycle.1"7 In some species cone disc shedding occurs cones shed discs predominately during the first 2 hr predominantly at the beginning of the dark cycle,58 after light onset. while in others, it reaches a maximum somewhat later in the photoperiod.4'6 It has been suggested that the Materials and Methods temporal relationship between cone disc shedding and the onset of darkness is analogous to the link Nineteen domestic cats were kept on a 12-hr light/ between rod disc shedding and the onset of light.9 12-hr dark cycle for 2 weeks to several months. Tem- We investigated the daily cycle of photoreceptor perature and humidity were also kept constant. disc shedding in domestic cats entrained to a 12-hr Room lighting (270 lux) was provided by overhead light/12-hr dark cycle. Cats have a duplex retina dom- fluorescent lamps. Water and cat chow were available inated by rod photoreceptors, but with a moderate at all times. Animals were killed at the following times population of cones10 that are distinguished easily (0 hr = lights on, 12 hr = lights off): 0, 1 (two cats), from rods because they are shorter and do not reach 2 (two cats), 3, 6, 9, 13, 14, 18 (three cats), 19, 20, the apical border of the RPE.11'12 The cones are con- 21, 22 (two cats), 23 hr. tacted by specialized sheet-like RPE processes that fill the space between the tips of the cones and the apical Fixation surface of the RPE.1112 Thus, disc packets shed by Cats were anesthetized by an initial intramuscular cones in this species are particularly easy to distin- dose of ketamine HC1 (Bristol); once sedation oc- guish from those shed by rods, since they remain curred (within a few minutes) they were given a lethal dose of sodium pentobarbital (Nembutal®, Abbott). For animals fixed during the dark period, anesthesia From the Department of Biological Sciences,* University of was done with illumination from a flashlight equipped California, Santa Barbara, Santa Barbara, California, and the Na- tional Eye Institute,! Bethesda, Maryland. with a red-transmitting filter or a safelight equipped Supported by National Eye Institute research grants EY-00888 with a Wratten No. 25 filter. For the animals fixed and EY-02082 and NEI Research Career Development Award EY- at 13, 14, 18 (two of three cats), 19, 20, 22 hr (one 00174 to SKF. of two cats), enucleation and dissection of the eyes Submitted for publication July 8, 1982. were done under red light. For those cats killed at 18 Reprint requests: Steven K. Fisher, Department of Biological Sciences, University of California, Santa Barbara, Santa Barbara, (one of three cats), 21, 22 (one of two cats), and 23 CA 93106. hr, anesthesia was administered under red light and, 0146-0404/83/0700/844/$ 1.40 © Association for Research in Vision and Ophthalmology 844 Downloaded from iovs.arvojournals.org on 10/01/2021 No. 7 ROD AND DISC CONE SHEDDING/Fisher er ol. 845 when respiration had stopped, the lights were turned This involved counting 10 to 20 sections for each on and enucleation of the eyes had begun. In all cases, specimen. The mean number of phagosomes/mm is enucleation and dissection of the eyes took less than derived from counts of each of several sections, and 10 min. the standard error was used as a measure of variability After enucleation, the cornea, lens, and as much between the different sections. Each section used for of the vitreous as possible were dissected away, and counting was separated from its nearest neighbor by the eye was immersed in a fixative composed of glu- at least 5 ixra to avoid duplication of phagosome taraldehyde and formaldehyde (1% each) in 0.086 M counts. Phagosomes within the cone sheaths were not sodium phosphate buffer (pH 7.2) with 20 mM CaCl2 counted in the "RPE phagosome" category but were added.14 They were kept in fixative for 12 to 24 hrs counted separately as cone phagosomes. Because of at 4 C and then washed several times in phosphate the relatively low number of cones, the cone phago- buffer with 4.5% sucrose and 20 mM CaCl2 at pH somes were tabulated as number of phagosomes/100 7.2. During the buffer wash, a notch was cut in the well-aligned cone sheaths. Since phagosomes tend to superior pole of the eye cup to allow orientation after stay in the center of the cone sheath as they ascend osmication. The eyes were post-fixed in 2% osmium to the RPE, a 1-jtm-thick section through a well- tetroxide (in veronal acetate buffer with 4.5% sucrose aligned cone outer segment and sheath will almost and 20 mM CaCl2 at pH 7.1) for 2 to 2V2 hr at 4 C, certainly reveal any phagosomes within that sheath. rinsed in distilled H2O, and stained overnight in 0.5% All slides were coded so that the two individuals doing aqueous uranyl acetate. After a brief wash in distilled counts did not know the time of fixation. H2O, the tissue was dehydrated in a cold ethanol-H20 The diameter of RPE phagosomes was measured, series, passed through propylene oxide, and embed- using an optical reticule, for cats killed at 1,2, and ded in Araldite 6005® (Cargille). While in absolute 6 hr after light onset and for phagosomes in the cone ethanol, the eyecup was divided into superior and sheaths of cats killed at 1 and 2 hr after light onset. inferior halves and the superior half further divided Small (0.4-0.8 nm diameter), homogeneous granules into two quadrants with the more temporal portion (distinct from phagosomes) were also counted in 1 including the area centralis. Only this quadrant was mm of RPE for each animal. used in our study. Measurements of outer segment length from pho- tomicrographs and of the areas under the curves con- Microscopy structed from phagosome frequency data were made using a Zeiss digital image processor (MOP-3). One micrometer thick sections were taken from the superior-temporal quadrant of one eye from each Results cat; the tapetal region just peripheral to the area cen- tralis was used because in the area centralis itself, Cat Tapetal Retinal Pigment Epithelium there is little or no space between cone outer segment tips and the apical border of the RPE (unpublished The RPE cells of the posterior tapetal region are observations). One micrometer thick sections for irregularly shaped because large choroidal capillaries phagosome counts were taken with a Sorvall MT2-B indent their basal surfaces (see Fig. 5A for example). ultramicrotome, placed on glass slides, and stained In longitudinal sections, the RPE cell depth, as mea- either with a solution of 0.1% toluidine blue and 0.1% sured from the apical to basal surfaces, varies from azure II in 0.5% aqueous sodium tetraborate or with 2 to 9 fxm; their width from one lateral border to the saturated, aqueous p-phenylenediamine. next is between 14 and 17 /xm when the section plane passes through the center of the nucleus. Thin sections (50-70 nm thick) were stained with Three major cytoplasmic inclusions can be rec- uranyl acetate and lead citrate and examined by elec- ognized by light microscopy in these cells: phago- tron microscopy. somes (phagocytosed packets of discs shed from un- derlying photoreceptors), melanin granules, and a Quantitative Data large population of homogeneously staining dense Phagosomes were identified by light microscopy on granules measuring 0.4 to 0.8 nm in diameter. Mature the basis of their size and staining characteristics (see melanin granules are found in all of our samples, but results). Phagosome counts were made using a Zeiss their frequency is low as would be expected from Universal Research Microscope fitted with a 63X retina overlying a tapetum. They are distinguished planapochromat objective at a total magnification of easily from phagosomes by their staining properties, 787.5 times.
Load more

Recommended publications
  • Structure of Cone Photoreceptors
    Progress in Retinal and Eye Research 28 (2009) 289–302 Contents lists available at ScienceDirect Progress in Retinal and Eye Research journal homepage: www.elsevier.com/locate/prer Structure of cone photoreceptors Debarshi Mustafi a, Andreas H. Engel a,b, Krzysztof Palczewski a,* a Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106-4965, USA b Center for Cellular Imaging and Nanoanalytics, M.E. Mu¨ller Institute, Biozentrum, WRO-1058, Mattenstrasse 26, CH 4058 Basel, Switzerland abstract Keywords: Although outnumbered more than 20:1 by rod photoreceptors, cone cells in the human retina mediate Cone photoreceptors daylight vision and are critical for visual acuity and color discrimination. A variety of human diseases are Rod photoreceptors characterized by a progressive loss of cone photoreceptors but the low abundance of cones and the Retinoids absence of a macula in non-primate mammalian retinas have made it difficult to investigate cones Retinoid cycle directly. Conventional rodents (laboratory mice and rats) are nocturnal rod-dominated species with few Chromophore Opsins cones in the retina, and studying other animals with cone-rich retinas presents various logistic and Retina technical difficulties. Originating in the early 1900s, past research has begun to provide insights into cone Vision ultrastructure but has yet to afford an overall perspective of cone cell organization. This review Rhodopsin summarizes our past progress and focuses on the recent introduction of special mammalian models Cone pigments (transgenic mice and diurnal rats rich in cones) that together with new investigative techniques such as Enhanced S-cone syndrome atomic force microscopy and cryo-electron tomography promise to reveal a more unified concept of cone Retinitis pigmentosa photoreceptor organization and its role in retinal diseases.
    [Show full text]
  • THE ROLE of ROM-1 in MAPNTAINING PHOTORECEPTOR STRUCTURE AM) VUBILITY, and a MATHEMATICAL MODEL EXPLOIUNG the Icinetics of NEURONAL DEGENERATION
    THE ROLE OF ROM-1 IN MAPNTAINING PHOTORECEPTOR STRUCTURE AM) VUBILITY, AND A MATHEMATICAL MODEL EXPLOIUNG THE ICINETiCS OF NEURONAL DEGENERATION Geoffrey Alïan Clarke A thesis submittd in cdormity with the requirements foi the degree of Worof Philosophy, Graduate Department of Mobdar and Medical Genetics, in the University of Toronto O Copyri@ by Geofffey AUan Clarke 2ûûû The author has gnmted a non- L'auteur a accordé une licence non exclusive licence ailowing the exclusive pennettaat à la National Library of Canada to Bibliothèque nationale du Canada de reprduce, 10- distnïute or sel reproduire, prêter, distribuer ou copies of this thesis in microfonn, vendre des copies de cette thèse sous paper or electronic formats. la forme de microfiche/nlm, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantiaî extracts firom it Ni la thèse ni des extraits substantiels may be printed or otherwise de ceiîe-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. Cana The Rok Of Rom-1 In MainWning Photoreceptor Structure and ViabUity, and a Matbernatical Mode1 Explorlng the ainetics of Neuronal Degeneration Geoffrey Ailan Clarke Department of Molecular and Medical Genetics University of Toronto Doctor of Philosophy,2000 Abstract Rom-1 and peripherinhds are homoIogous membrane proteins localized to the disk rims of photoreceptor outer segments (OSs), where they are postulated to be critical for disk -1- morphogenesis, OS renewal, and the maintenance of OS structure.
    [Show full text]
  • The Influence of Light on Cone Disk Shedding in the Lizard, Sceloporus Occidentalis
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by PubMed Central REGULAR ARTICLES The Influence of Light on Cone Disk Shedding in the Lizard, Sceloporus occidentalis STEVEN A. BERNSTEIN, DAVID J . BREDING, and STEVEN K . FISHER Department of Biological Sciences, University of California, Santa Barbara, Santa Barbara 93106 ABSTRACT The lizard, Sceloporus occidentalis has an all-cone retina. In lizards maintained on a 12-h light:12-h dark (12L:12D) cycle, a burst of cone outer segment (COS) shedding occurs 2 h after light offset (1400 h circadian time) (Young, R . W ., 1977, /. Ultrastruct. Res . 61 :172- 72). In this investigation, we studied the effect of different lighting regimes on the pattern of cone disk shedding in this species. When lizards entrained to a 121-:12D cycle are kept in constant darkness (DD), the shedding peak is advanced -2 h and the magnitude of shedding is reduced to 30% of control. COS increased in mean length from 12 Am in controls to 14 Am after one cycle in DD and maintained this length during a second cycle in DD. In constant light (LL), disk shedding was damped to -10% of control values. Shedding synchrony in LL was also perturbed and therefore cyclic shedding bursts could not be distinguished . During LL there was a much larger increase in COS mean length than in DD . After one cycle of LL, COS length was 15 Am and after two cycles COS length exceeded 17 Am . When lizards entrained to 121-:1 2D are shifted to a 6L:18D regimen, the first shedding cycle is biphasic .
    [Show full text]
  • RPE Cell Biology David William 2020 Review
    NOTICE WARNING CONCERNING COPYRIGHT RESTRICTIONS The copyright law of the United States [Title 17, United States Code] governs the making of photocopies or other reproductions of copyrighted material. Under certain conditions specified in the law, libraries and archives are authorized to furnish a photocopy or other reproduction. One of these specified conditions is that the reproduction is not to be used for any purpose other than private study, scholarship, or research. If a user makes a request for, or later uses, a photocopy or reproduction for purposes in excess of "fair use," that use may be liable for copyright infringement. This institution reserves the right to refuse to accept a copying order if, in its judgement, fullfillment of the order would involve violation of copyright law. No further reproduction and distribution of this copy is permitted by transmission or any other means. Progress in Retinal and Eye Research xxx (xxxx) xxxx Contents lists available at ScienceDirect Progress in Retinal and Eye Research journal homepage: www.elsevier.com/locate/preteyeres ☆ The cell biology of the retinal pigment epithelium Aparna Lakkarajua,1, Ankita Umapathyb,c,1, Li Xuan Tana, Lauren Danieled, Nancy J. Philpe, ∗ Kathleen Boesze-Battagliad, David S. Williamsb,c, a Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA b Department of Ophthalmology and Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA,USA c Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA,USA d Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA e Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA ARTICLE INFO ABSTRACT Keywords: The retinal pigment epithelium (RPE), a monolayer of post-mitotic polarized epithelial cells, strategically si- Phagocytosis tuated between the photoreceptors and the choroid, is the primary caretaker of photoreceptor health and Phagosome maturation function.
    [Show full text]
  • Photoreceptor Autophagy: Effects of Light History on Number and Opsin Content of Degradative Vacuoles
    Photoreceptor Autophagy: Effects of Light History on Number and Opsin Content of Degradative Vacuoles Charlotte E. Reme´,1 Uwe Wolfrum,2 Cornelia Imsand,1 Farhad Hafezi,1 and Theodore P. Williams3 PURPOSE. To investigate whether regulation of rhodopsin levels as a response to changed lighting environment is performed by autophagic degradation of opsin in rod inner segments (RISs). METHODS. Groups of albino rats were kept in 3 lux or 200 lux. At 10 weeks of age, one group was transferred from 3 lux to 200 lux, another group was switched from 200 lux to 3 lux, and two groups remained in their native lighting (baselines). Rats were killed at days 1, 2, and 3 after switching. Another group was switched from 3 lux to 200 lux, and rats were killed at short intervals after the switch. Numbers of autophagic vacuoles (AVs) in RISs were counted, and immunogold labeling was performed for opsin and ubiquitin in electron microscopic sections. RESULTS. The number of AVs increased significantly after switching from 3 lux to 200 lux at days 1 and 2 and declined at day 3, whereas the reverse intensity change did not cause any increase. Early time points after change from 3 lux to 200 lux showed a significant increase of AVs 2 and 3 hours after switching. Distinct opsin label was observed in AVs of rats switched to 200 lux. Ubiquitin label was present in all investigated specimens and was also seen in AVs especially in 200-lux immigrants. CONCLUSIONS. Earlier studies had shown that an adjustment to new lighting environment is per- formed by changes in rhodopsin levels in ROSs.
    [Show full text]
  • A Diurnal Rhythm in Opsin Content of RQDQ Pipiens Rod Inner Segments Alon C
    Investigative Ophthalmology & Visual Science, Vol. 29, No. 7, July 1988 Copyright © Association for Research in Vision and Ophthalmology A Diurnal Rhythm in Opsin Content of RQDQ pipiens Rod Inner Segments Alon C. Bird,* John G. Flannery.f ond Dean Bokft Quantitative electron microscope immunocytochemistry, employing an antibody specific to opsin, was used to evaluate the amount and location of opsin in Rana pipiens rod photoreceptors throughout a 24 hr light/dark cycle. We found a distinct diurnal rhythm in the density of anti-opsin labeling of the rough endoplasmic reticulum (RER) and Golgi apparatus in the myoid region of the rod inner segment. Opsin labeling of these organelles was lowest at light onset, increasing thereafter by three- to four- fold, and remained high until 2 hr into the dark phase. A fall in labeling density occurred within the following 4 hr, and remained low for the remainder of the dark phase. Our finding of a diurnal rhythm regulating inner segment opsin transport in Rana pipiens contrasts with published observations on outer segment membrane turnover, since it has been shown that the rates of disc formation and disc shedding are governed by environmental lighting alone in this species. These results imply that there is opsin pooling in the inner segment during the first 14 hr of a 24 hr light/dark cycle; thereafter the loss of inner segment opsin due to mobilization of this protein from the Golgi exceeds the rate of formation of new opsin. There was no evidence of accumulation of opsin-containing vesicles near the cilium or in the ellipsoid just prior to light onset.
    [Show full text]
  • The Influence of Light on Cone Disk Shedding in the Lizard, Sceloporus Occidentalis
    Published August 1, 1984 REGULAR ARTICLES The Influence of Light on Cone Disk Shedding in the Lizard, Sceloporus occidentalis STEVEN A. BERNSTEIN, DAVID J . BREDING, and STEVEN K . FISHER Department of Biological Sciences, University of California, Santa Barbara, Santa Barbara 93106 ABSTRACT The lizard, Sceloporus occidentalis has an all-cone retina. In lizards maintained on a 12-h light:12-h dark (12L:12D) cycle, a burst of cone outer segment (COS) shedding occurs 2 h after light offset (1400 h circadian time) (Young, R . W ., 1977, /. Ultrastruct. Res . 61 :172- 72). In this investigation, we studied the effect of different lighting regimes on the pattern of cone disk shedding in this species. When lizards entrained to a 121-:12D cycle are kept in Downloaded from constant darkness (DD), the shedding peak is advanced -2 h and the magnitude of shedding is reduced to 30% of control. COS increased in mean length from 12 Am in controls to 14 Am after one cycle in DD and maintained this length during a second cycle in DD. In constant light (LL), disk shedding was damped to -10% of control values. Shedding synchrony in LL was also perturbed and therefore cyclic shedding bursts could not be distinguished . During LL there was a much larger increase in COS mean length than in DD . After one cycle of LL, on April 2, 2017 COS length was 15 Am and after two cycles COS length exceeded 17 Am . When lizards entrained to 121-:1 2D are shifted to a 6L:18D regimen, the first shedding cycle is biphasic .
    [Show full text]
  • The Function of Snare Complex Proteins in Photoreceptor Outer Segment Formation Shows Support for the Classical E Agination Model
    )ORULGD6WDWH8QLYHUVLW\/LEUDULHV 2020 The Function of Snare Complex Proteins in Photoreceptor Outer Segment Formation Shows Support for the Classical Evagination Model Carley Marie Huffstetler Follow this and additional works at DigiNole: FSU's Digital Repository. For more information, please contact [email protected] THE FLORIDA STATE UNIVERSITY COLLEGE OF ARTS AND SCIENCES THE FUNCTION OF SNARE COMPLEX PROTEINS IN PHOTORECEPTOR OUTER SEGMENT FORMATION SHOWS SUPPORT FOR THE CLASSICAL EVAGINATION MODEL By CARLEY MARIE HUFFSTETLER A Thesis submitted to the Department of Chemistry and Biochemistry In partial fulfillment of the requirements for Honors in the Major Degree Awarded: Spring, 2020 The Members of the Committee approve the thesis of Carley Marie Huffstetler defended on April 23rd, 2020. __________________________________________ James M. Fadool, Ph.D. Directing Professor Department of Biological Sciences __________________________________________ Bridget A. DePrince, Ph.D Committee Member Department of Chemistry and Biochemistry __________________________________________ Justin G. Kennemur, Ph.D Committee Member Department of Chemistry and Biochemistry ACKNOWLEDGEMENTS I would like to give a huge thanks to Dr. James Fadool for all of his teaching, training, and guidance over the past few years and for giving me the opportunity and tools to have learned so much in his lab. I would also especially like to thank Dr. Bridget DePrince and Dr. Justin Kennemur for serving on my committee. Thank you to Sixian Song, Jacob Dilliplane, and Jacob Myhre for friendship and conversation in the lab. Thank you to Dr. Debra Fadool and all the members of her lab for providing me with additional guidance, friendship, and a great weekly lab meeting! Finally, thank you to the FSU-CRC and The Foundation Fighting Blindness for funding our research.
    [Show full text]
  • Kif17 Phosphorylation Regulates Photoreceptor Outer Segment Turnover Tylor R
    Lewis et al. BMC Cell Biology (2018) 19:25 https://doi.org/10.1186/s12860-018-0177-9 RESEARCHARTICLE Open Access Kif17 phosphorylation regulates photoreceptor outer segment turnover Tylor R. Lewis1, Sean R. Kundinger2, Brian A. Link1, Christine Insinna1,3 and Joseph C. Besharse1,2* Abstract Background: KIF17, a kinesin-2 motor that functions in intraflagellar transport, can regulate the onset of photoreceptor outer segment development. However, the function of KIF17 in a mature photoreceptor remains unclear. Additionally, the ciliary localization of KIF17 is regulated by a C-terminal consensus sequence (KRKK) that is immediately adjacent to a conserved residue (mouse S1029/zebrafish S815) previously shown to be phosphorylated by CaMKII. Yet, whether this phosphorylation can regulate the localization, and thus function, of KIF17 in ciliary photoreceptors remains unknown. Results: Using transgenic expression in zebrafish photoreceptors, we show that phospho-mimetic KIF17 has enhanced localization along the cone outer segment. Importantly, expression of phospho-mimetic KIF17 is associated with greatly enhanced turnover of the photoreceptor outer segment through disc shedding in a cell- autonomous manner, while genetic mutants of kif17 in zebrafish and mice have diminished disc shedding. Lastly, cone expression of constitutively active tCaMKII leads to a kif17-dependent increase in disc shedding. Conclusions: Taken together, our data support a model in which phosphorylation of KIF17 promotes its photoreceptor outer segment localization and disc shedding, a process essential for photoreceptor maintenance and homeostasis. While disc shedding has been predominantly studied in the context of the mechanisms underlying phagocytosis of outer segments by the retinal pigment epithelium, this work implicates photoreceptor- derived signaling in the underlying mechanisms of disc shedding.
    [Show full text]
  • Membranous Inclusions in the Retinal Pigment Epithelium: Phagosomes and Myeloid Bodies
    J. Anat. (1971), 110, 1, pp. 91-104 91 With 6 figures Printed in Great Britain Membranous inclusions in the retinal pigment epithelium: phagosomes and myeloid bodies J. MARSHALL AND P. L. ANSELL Department ofAnatomy, Institute of Ophthalmology, Judd Street, London, WClH 9QS (Accepted 9 June 1971) INTRODUCTION The first ultrastructural description of membrane aggregations in the retinal pig- ment epithelium was by Porter (1957), and was followed by a more detailed account by Porter & Yamada (1960). These authors described two systems in the frog, both consisting of a compact lattice of membrane-lined tubules, with a stacking periodicity which resembled that of the lamellae of the receptor outer segments. The first of these systems was associated with the endoplasmic reticulum and was described as shaped like biconvex lenses. These structures were regarded by Porter & Yamada as equi- valent to the myeloid bodies described by earlier histologists (Kuihne, 1879). The second type of lattice system was described as globular and osmiophilic. These structures were designated lamellated lipid or lipo-protein granules. Since then lamellar systems, termed myeloid bodies, have been identified in several species of amphibians (Porter & Yamada, 1960), reptiles (Yamada, 1961) and birds (Nishida, 1964). Dowling & Gibbons (1961) were the first to identify lamellar inclusions in a mam- malian retina, and, though they listed certain differences between their observations and those of Porter & Yamada, they used the term myeloid bodies to describe these structures. In 1962, however, Dowling & Gibbons recognized that these differences (notably that the mammalian inclusions were bounded by a limiting membrane) were significant, and introduced the term inclusion bodies to describe the mammalian inclusions.
    [Show full text]
  • The Ageing Retina: Physiology Or Pathology
    Eye (1987) 1, 282-295 The Ageing Retina: Physiology or Pathology JOHN MARSHALL London Summary The human'fetina is a unique component of the nervous system in that throughout life it is continuously exposed to optical radiation between 400 and 1400 nm. The physiology of the ageing retina and the regression in visual performance with age cannot therefore be studied in isolation, or discriminated, from the life long cumulative effects of radiant exposure. This paper describes the spectrum of age related changes in the retina as they merge imperceptibly between declining visual function and overt pathology. Functional Loss ponents, the larger one being diminished Virtually every measure of visual function transmission by the ageing lens and a smaller demonstrates declining performance with one induced by neuronal changes in the age­ increasing age.! However, since all the com­ ing retina and cortex. ponents of the eye age in different ways it is Age related degradations in visual acuity5.6 essential when assessing changes in retinal or and contrast sensitivity7,8 have been docu­ neural function to allow for changes in the mented for many years9 and are especially stimulous incident upon the retina due to evident over the age of 60 years. 5 Recently the either perturbations in the optic media or use of sinusoidal grating patterns generated physiological processes in the anterior eye. by a laser interferometerlO has enabled the For example, in the older eye the retinal irra­ independent assessment of degradation of the diance achieved by a given source with a given image quality by the optic media and the geometry will be less than that in a young eye effective loss in resolving power of the neuro­ because of a reduced pupillary diameter nal components in the visual system.Il,12 The (senile miosis), and decreasing transmission conclusion from such studies is that the age and increasing fluorescence properties of the related deterioration in contrast sensitivity is cornea and lens.
    [Show full text]
  • The Effects of Ionizing Radiation on the Light
    THE EFFECTS OF IONIZING RADIATION ON THE LIGHT SENSING ELEMENTS OF THE RETINA Michael J. Malachowskl Ph.D. Thesis August 197B rftrlhU/niicdSliaiCoitmr Division of Biology and Medicine Lawrence Berkeley Laboratory University of California Berkeley, CA 94720 -iii- CONTENTS ACKNOWLEDGMENTS viL i ABSTRACT lx I. INTRODUCTION 1 Background • 1 The retina 1 Evolution of the light sensing elements 2 Structure 5 Eye embryology 5 Membranes * 9 Vitamin A 14 Visual pigments 14 Retinal rod outer-segment lamella 15 Figment epithelium IB Muller cells 19 Function > 20 Photochemistry • 23 Biopotentials 23 Particle Radiation 31 Background 31 Dosimetry IV Stopping power formula .,,.••••• 39 Pathology 52 Background .... 52 Genetic disorders 55 Nonionizing radiation 57 Ionizing radiation ..... ..... 61 Retinal degeneration 66 II. MATERIALS AND METHODS . t 68 Animals 68 Necturus maculosus ..*.. • 68 Mus negrus 0C57 68 Irradiation Techniques 68 Autoradiography 74 Histology 77 Necturus maculosus ••* * 77 Mus negrus tfC57 78 Ultrastructure 79 Light microscopy 79 Scanning electron microscopy 79 Transmission electron microscopy * 80 Autoradiography 80 Scoring : 80 Necturus maculosus * 80 Mus negrus //C57 T 83 Protein synthesis 63 Outer-segment protein transit 84 -iv- III. RESULTS 85 Necturus maculosus • . 85 Ulirestructure B5 Light microscopy 85 Scanning electron microscopy 85 Transmission electron micrscopy . - . t 102 Damage evaluation and scoring 103 Mus negrus #C57 125 Ultrastructure 125 Light microscopy 130 Scanning electron microscopy 148 Transmission electron microscopy 166 IV. DISCUSSION 170 Thermodynamic Model 170 Membrane Synthesis 173 A Model of Disc Formation Based on Electron Microscopy . • 180 Radiation Pathology 18b Necturus maculosus ........... 187 Mus negrus tfC57 7 188 Autoradiography 190 V. CONCLUSIONS 191 REFERENCES 194 APPENDIX I - Necturus maculosus light sensing elements ...
    [Show full text]