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Temple SE, How MJ, Powell SB, Gruev V, Marshall NJ, Roberts NW. Thresholds of polarization vision in octopuses. J Exp Biol 2021; 224:238090. [PMID: 33602676 PMCID: PMC8077535 DOI: 10.1242/jeb.240812] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 02/11/2021] [Indexed: 12/16/2022]
Abstract
Polarization vision is widespread in nature, mainly among invertebrates, and is used for a range of tasks including navigation, habitat localization and communication. In marine environments, some species such as those from the Crustacea and Cephalopoda that are principally monochromatic, have evolved to use this adaptation to discriminate objects across the whole visual field, an ability similar to our own use of colour vision. The performance of these polarization vision systems varies, and the few cephalopod species tested so far have notably acute thresholds of discrimination. However, most studies to date have used artificial sources of polarized light that produce levels of polarization much higher than found in nature. In this study, the ability of octopuses to detect polarization contrasts varying in angle of polarization (AoP) was investigated over a range of different degrees of linear polarization (DoLP) to better judge their visual ability in more ecologically relevant conditions. The ‘just-noticeable-differences’ (JND) of AoP contrasts varied consistently with DoLP. These JND thresholds could be largely explained by their ‘polarization distance’, a neurophysical model that effectively calculates the level of activity in opposing horizontally and vertically oriented polarization channels in the cephalopod visual system. Imaging polarimetry from the animals’ natural environment was then used to illustrate the functional advantage that these polarization thresholds may confer in behaviourally relevant contexts. Summary: Octopuses are highly sensitive to small changes in the angle of polarization (<1 deg contrast), even when the degree of polarization is low, which may confer a functional advantage in behaviourally relevant contexts.
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Affiliation(s)
- Shelby E Temple
- Ecology of Vision Group, School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK.,Azul Optics Ltd, Henleaze, Bristol BS9 4QG, UK
| | - Martin J How
- Ecology of Vision Group, School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Samuel B Powell
- Sensory Neurobiology Group, Queensland Brain Institute, University of Queensland, Brisbane, QLD 4072, Australia
| | - Viktor Gruev
- Biosensors Lab, Electrical and Computer Engineering, University of Illinois, Urbana, IL 61801, USA
| | - N Justin Marshall
- Sensory Neurobiology Group, Queensland Brain Institute, University of Queensland, Brisbane, QLD 4072, Australia
| | - Nicholas W Roberts
- Ecology of Vision Group, School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
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Frau S, Novales Flamarique I, Keeley PW, Reese BE, Muñoz-Cueto JA. Straying from the flatfish retinal plan: Cone photoreceptor patterning in the common sole (Solea solea) and the Senegalese sole (Solea senegalensis). J Comp Neurol 2020; 528:2283-2307. [PMID: 32103501 DOI: 10.1002/cne.24893] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/24/2020] [Accepted: 02/24/2020] [Indexed: 11/09/2022]
Abstract
The retinas of nonmammalian vertebrates have cone photoreceptor mosaics that are often organized as highly patterned lattice-like distributions. In fishes, the two main lattice-like patterns are composed of double cones and single cones that are either assembled as interdigitized squares or as alternating rows. The functional significance of such orderly patterning is unknown. Here, the cone mosaics in two species of Soleidae flatfishes, the common sole and the Senegalese sole, were characterized and compared to those from other fishes to explore variability in cone patterning and how it may relate to visual function. The cone mosaics of the common sole and the Senegalese sole consisted of single, double, and triple cones in formations that differed from the traditional square mosaic pattern reported for other flatfishes in that no evidence of higher order periodicity was present. Furthermore, mean regularity indices for single and double cones were conspicuously lower than those of other fishes with "typical" square and row mosaics, but comparable to those of goldfish, a species with lattice-like periodicity in its cone mosaic. Opsin transcripts detected by quantitative polymerase chain reaction (sws1, sws2, rh2.3, rh2.4, lws, and rh1) were uniformly expressed across the retina of the common sole but, in the Senegalese sole, sws2, rh2.4, and rh1 were more prevalent in the dorsal retina. Microspectrophotometry revealed five visual pigments in the retina of the common sole [S(472), M(523), M(536), L(559), and rod(511)] corresponding to the repertoire of transcripts quantified except for sws1. Overall, these results indicate a loss of cone mosaic patterning in species that are primarily nocturnal or dwell in low light environments as is the case for the common sole and the Senegalese sole. The corollary is that lattice-like patterning of the cone mosaic may improve visual acuity. Ecological and physiological correlates derived from observations across multiple fish taxa that live in low light environments and do not possess lattice-like cone mosaics are congruent with this claim.
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Affiliation(s)
- Sara Frau
- Department of Biology, Faculty of Marine and Environmental Sciences, University of Cádiz, The European University of the Seas (SEA-EU), Puerto Real, Spain
| | - Iñigo Novales Flamarique
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.,Department of Biology, University of Victoria, Victoria, British Columbia, Canada
| | - Patrick W Keeley
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, California, USA
| | - Benjamin E Reese
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, California, USA.,Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California, USA
| | - José A Muñoz-Cueto
- Department of Biology, Faculty of Marine and Environmental Sciences, University of Cádiz, The European University of the Seas (SEA-EU), Puerto Real, Spain
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3
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Swimming behaviour tunes fish polarization vision to double prey sighting distance. Sci Rep 2019; 9:944. [PMID: 30700806 PMCID: PMC6353921 DOI: 10.1038/s41598-018-37632-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 12/07/2018] [Indexed: 11/17/2022] Open
Abstract
The analysis of the polarization of light expands vision beyond the realm of colour and intensity and is used for multiple ecological purposes among invertebrates including orientation, object recognition, and communication. How vertebrates use polarization vision as part of natural behaviours is widely unknown. In this study, I tested the hypothesis that polarization vision improves the detection of zooplankton prey by the northern anchovy, Engraulis mordax, the only vertebrate with a demonstrated photoreceptor basis explaining its polarization sensitivity. Juvenile anchovies were recorded free foraging on zooplankton under downwelling light fields of varying percent polarization (98%, 67%, 19%, and 0% - unpolarized light). Analyses of prey attack sequences showed that anchovies swam in the horizontal plane perpendicular, on average, to the polarization direction of downwelling light and attacked prey at pitch angles that maximized polarization contrast perception of prey by the ventro-temporal retina, the area devoted to polarization vision in this animal. Consequently, the mean prey location distance under polarized light was up to 2.1 times that under unpolarized conditions. All indicators of polarization vision mediated foraging were present under 19% polarization, which is within the polarization range commonly found in nature during daylight hours. These results demonstrate: (i) the first use of oriented swimming for enhancing polarization contrast detection of prey, (ii) its relevance to improved foraging under available light cues in nature, and (iii) an increase in target detection distance that is only matched by polarization based artificial systems.
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Novales Flamarique I. A vertebrate retina with segregated colour and polarization sensitivity. Proc Biol Sci 2018; 284:rspb.2017.0759. [PMID: 28878058 DOI: 10.1098/rspb.2017.0759] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Accepted: 07/25/2017] [Indexed: 11/12/2022] Open
Abstract
Besides colour and intensity, some invertebrates are able to independently detect the polarization of light. Among vertebrates, such separation of visual modalities has only been hypothesized for some species of anchovies whose cone photoreceptors have unusual ultrastructure that varies with retinal location. Here, I tested this hypothesis by performing physiological experiments of colour and polarization discrimination using the northern anchovy, Engraulis mordax Optic nerve recordings showed that the ventro-temporal (VT), but not the ventro-nasal (VN), retina was polarization sensitive, and this coincided with the exclusive presence of polarization-sensitive photoreceptors in the VT retina. Spectral (colour) sensitivity recordings from the VN retina indicated the contribution of two spectral cone mechanisms to the optic nerve response, whereas only one contributed to the VT retina. This was supported by the presence of only one visual pigment in the VT retina and two in the VN retina, suggesting that only the VN retina was associated with colour sensitivity. Behavioural tests further demonstrated that anchovies could discriminate colour and the polarization of light using the ventral retina. Thus, in analogy with the visual system of some invertebrates, the northern anchovy has a retina with segregated retinal pathways for colour and polarization vision.
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Affiliation(s)
- Iñigo Novales Flamarique
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada V3J 4M5 .,Department of Biology, University of Victoria, Victoria, British Columbia, Canada V8W 2Y2
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5
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Fritsch R, Ullmann JFP, Bitton PP, Collin SP, Michiels NK. Optic-nerve-transmitted eyeshine, a new type of light emission from fish eyes. Front Zool 2017; 14:14. [PMID: 28261313 PMCID: PMC5327540 DOI: 10.1186/s12983-017-0198-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 02/15/2017] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Most animal eyes feature an opaque pigmented eyecup to assure that light can enter from one direction only. We challenge this dogma by describing a previously unknown form of eyeshine resulting from light that enters the eye through the top of the head and optic nerve, eventually emanating through the pupil as a narrow beam: the Optic-Nerve-Transmitted (ONT) eyeshine. We characterize ONT eyeshine in the triplefin blenny Tripterygion delaisi (Tripterygiidae) in comparison to three other teleost species, using behavioural and anatomical observations, spectrophotometry, histology, and magnetic resonance imaging. The study's aim is to identify the factors that determine ONT eyeshine occurrence and intensity, and whether these are specifically adapted for that purpose. RESULTS ONT eyeshine intensity benefits from locally reduced head pigmentation, a thin skull, the gap between eyes and forebrain, the potential light-guiding properties of the optic nerve, and, most importantly, a short distance between the head surface and the optic nerves. CONCLUSIONS The generality of these factors and the lack of specifically adapted features implies that ONT eyeshine is widespread among small fish species. Nevertheless, its intensity varies considerably, depending on the specific combination and varying expression of common anatomical features. We discuss whether ONT eyeshine might affect visual performance, and speculate about possible functions such as predator detection, camouflage, and intraspecific communication.
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Affiliation(s)
- Roland Fritsch
- Institute of Evolution and Ecology, University of Tübingen, 72076 Tübingen, Baden-Württemberg Germany
| | - Jeremy F P Ullmann
- Centre for Advanced Imaging, University of Queensland, Brisbane, 4072 Queensland Australia.,Department of Neurology, Boston Children's Hospital & Harvard Medical School, Boston, MA 02115 USA
| | - Pierre-Paul Bitton
- Institute of Evolution and Ecology, University of Tübingen, 72076 Tübingen, Baden-Württemberg Germany
| | - Shaun P Collin
- School of Biological Sciences and the Oceans Institute, University of Western Australia, Crawley, 6009 Western Australia Australia
| | - Nico K Michiels
- Institute of Evolution and Ecology, University of Tübingen, 72076 Tübingen, Baden-Württemberg Germany
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Kamermans M, Hawryshyn C. Teleost polarization vision: how it might work and what it might be good for. Philos Trans R Soc Lond B Biol Sci 2011; 366:742-56. [PMID: 21282178 DOI: 10.1098/rstb.2010.0211] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In this review, we will discuss the recent literature on fish polarization vision and we will present a model on how the retina processes polarization signals. The model is based on a general retinal-processing scheme and will be compared with the available electrophysiological data on polarization processing in the retina. The results of this model will help illustrate the functional significance of polarization vision for both feeding behaviour and navigation. First, we examine the linkage between structure and function in polarization vision in general.
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Affiliation(s)
- Maarten Kamermans
- Retinal Signal Processing, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
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Koch PC, Heß M. Topographic mapping of retinal neurons in the european anchovy by nuclear staining and immunohistochemistry. J Neurosci Res 2011; 89:1316-30. [DOI: 10.1002/jnr.22651] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 02/14/2011] [Accepted: 03/02/2011] [Indexed: 11/09/2022]
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Roberts NW, Porter ML, Cronin TW. The molecular basis of mechanisms underlying polarization vision. Philos Trans R Soc Lond B Biol Sci 2011; 366:627-37. [PMID: 21282166 PMCID: PMC3049014 DOI: 10.1098/rstb.2010.0206] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The underlying mechanisms of polarization sensitivity (PS) have long remained elusive. For rhabdomeric photoreceptors, questions remain over the high levels of PS measured experimentally. In ciliary photoreceptors, and specifically cones, little direct evidence supports any type of mechanism. In order to promote a greater interest in these fundamental aspects of polarization vision, we examined a varied collection of studies linking membrane biochemistry, protein-protein interactions, molecular ordering and membrane phase behaviour. While initially these studies may seem unrelated to polarization vision, a common narrative emerges. A surprising amount of evidence exists demonstrating the importance of protein-protein interactions in both rhabdomeric and ciliary photoreceptors, indicating the possible long-range ordering of the opsin protein for increased PS. Moreover, we extend this direction by considering how such protein paracrystalline organization arises in all cell types from controlled membrane phase behaviour and propose a universal pathway for PS to occur in both rhabdomeric and cone photoreceptors.
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Affiliation(s)
- Nicholas W Roberts
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK.
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10
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Triple cones in the retinae of three anchovy species: Engraulis encrasicolus, Cetengraulis mysticetus and Anchovia macrolepidota (Engraulididae, Teleostei). Vision Res 2009; 49:1569-82. [DOI: 10.1016/j.visres.2009.03.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Revised: 02/07/2009] [Accepted: 03/20/2009] [Indexed: 11/19/2022]
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Hess M, Melzer RR, Eser R, Smola U. The structure of anchovy outer retinae (Engraulididae, Clupeiformes) — A comparative light- and electron-microscopic study using museum-stored material. J Morphol 2006; 267:1356-80. [PMID: 17051549 DOI: 10.1002/jmor.10482] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The outer retinal architecture of Engraulididae is uncommon among vertebrates. In some anchovies, e.g., Anchoa, two cone types are arranged alternating in long photoreceptor chains, i.e., polycones. The cones have radially oriented outer segment lamellae in close contact with a complex guanine tapetum, most probably subserving polarization contrast vision. To clarify the distribution of the aberrant polycone architecture within the Engraulididae and to provide indications about polycone evolution, the outer retina morphology of 16 clupeoid species was investigated by light and electron microscopy, predominantly using museum-stored material. The outgroup representatives of four clupeid subfamilies (Clupeonella cultriventris, Dorosoma cepedianum, Ethmalosa fimbriata, Pellonula leonensis) show a row pattern of double cones, partially with single cones at defined positions and a pigment epithelium with lobopodial protrusions containing melanin. The pristigasterid Ilisha africana has double rows of single cones lying between linear curtains of pigment epithelium processes filled with minute crystallites and melanin concentrated near their vitreal tips. Within the Engraulididae, two main architectures are found: Coilia nasus and Thryssa setirostris have linear multiple cones or polycones separated by long pigment epithelium barriers containing tapetal crystallites and melanin in the tips (also found in Setipinna taty), whereas Anchoviella alleni, Encrasicholina heteroloba, Engraulis encrasicolus, Engraulis mordax, Lycengraulis batesii, and Stolephorus indicus exhibit the typical polycone architecture. Cetengraulis mysticetus and Lycothrissa crocodilus show cone patterns and pigment epithelium morphology differing from the other anchovy species. The sets of characters are compared, corroborated with the previous knowledge on clupeoid retinae and discussed in terms of functional morphology and visual ecology. A scenario on polycone evolution is developed that may serve as an aid for the reconstruction of engraulidid phylogeny. Furthermore, this study demonstrates the suitability of museum material for morphological studies, even at the electron microscopic level.
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Affiliation(s)
- Martin Hess
- Biozentrum der Ludwig-Maximilians-Universität, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany.
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Haacke C, Hess M, Melzer RR, Gebhart H, Smola U. Fine structure and development of the retina of the grenadier anchovy Coilia nasus (Engraulididae, Clupeiformes). J Morphol 2001; 248:41-55. [PMID: 11268057 DOI: 10.1002/jmor.1019] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A study of the morphogenesis of the grenadier anchovy retina was undertaken using light and electron microscopy. Five developmental stages from prelarvae 3 days after fertilization to adult fish were studied. In addition to the general morphology of the eye and retina, special emphasis was given to the development of the photoreceptors and pigment epithelium (PE). The earliest retinae showing structural features indicative of a functioning eye are pure cone retinae composed of rows of alternating long and short cones forming a transient, tesselated pattern. At this stage there is a conventional PE containing melanin. In older stages cone rows are separated by the newly formed rods and by PE wedges filled with diffusely reflecting guanine crystallites. The findings are compared with the retinae of other engraulidids and with the development of teleost retinae in general. Moreover, the observed structural changes are discussed with respect to the photic habitat conditions of these anadromous fish that move between coastal waters, estuary, and river.
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Affiliation(s)
- C Haacke
- Zoologisches Institut der Universität, München, Germany
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Studies on the photoreceptors ofAnchoa mitchilliandA. hepsetus(Engraulidae) with particular reference to the cones. ACTA ACUST UNITED AC 1997. [DOI: 10.1098/rstb.1978.0017] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Photoreceptors of anchoviesAnchoa mitchilliandA. hepsetusconsist of normal rods and two unusual kinds of cones. The latter lie in single vertical rows, and the rods lie between them. Both participate in photomechanical movements, and movement of the cones is closely coordinated with that of pigment cell processes. There are long cones having a cuneate outer segment and short cones having a bilobed outer segment. Long and short (bifid) cones alternate within a row and are staggered between adjacent rows. Both kinds possess calycal processes; long cones have a lateral sac or accessory outer segment. The long and short cones are associated to form a structure called a cone unit, which consists of the outer segment and ellipsoid of a long cone joined to two outer segment lobes of two adjacent short cones. The lobes of the latter are partly enclosed by the ellipsoid of the long cone. A cone row consists of a row of cone units isolated from each other by processes of the pigment epithelium containing stacks of guanine crystals which form a tapetum. Dorsal and ventral faces of inner segments have contact zones characterized by subsurface cisternae. Lamellae in the cone outer segments are arranged longitudinally with respect to the cell axis and short and long cone lamellae are perpendicular to each other; lamellae of the rods are transverse. Long cone lamellae are perpendicular to the cone row, and in the central retina are almost horizontal to the long axis of the body. Some vesicular/tubular structures also occur in the cone outer segments. Outer and inner segments of cones are joined by a broad connecting structure containing a stalk and root portion corresponding to a modified and reduced cilium shaft and centriole, respectively. The rod has a typical connecting stalk. Mitochondria of cone ellipsoids have expanded perimitochondrial spaces between outer and inner membranes. The organization of the anchovy cones is compared with that of other vertebrates. It is suggested that the cone unit may be a two channel analyser for the detection of plane polarized light and function in conjunction with the overlying reflector of regularly arranged platelets.
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Fite KV, Bengston L, Doran P. Retinal pigment epithelial correlates of avian retinal degeneration: electron microscopic analysis. J Comp Neurol 1985; 231:310-22. [PMID: 3968241 DOI: 10.1002/cne.902310303] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The delayed amelanotic (DAM) strain of domestic chicken is characterized by an early, developmental onset of choroidal inflammation and destruction of both feather and choroidal melanocytes. Secondarily, retinal pigment epithelial (RPE) cells in the peripapillary region develop abnormalities, and a series of progressive histopathological changes ensues which includes reduction and ultimate loss of RPE-melanin granules and RPE-cell atrophy. The earliest sign of RPE-cell abnormality is a dramatic alteration in the distribution of intracellular melanin granules. Apical processes also show a lessening of contact with photoreceptor outer segments, leading in more advanced stages to their retraction and development of retinal detachments. Other progressive alterations in RPE cells include disorganization and loss of basal infoldings; size reductions and density increases in both mitochondria and myeloid bodies from early to advanced stages; appearance of large macrophages in the subretinal space; Loss of intercellular junctional complexes; and progressive reduction in the density of melanin granules. These abnormalities appear to spread in a cell-by-cell, radial pattern, until widespread areas of the retina become severely pathologic and atrophic. The DAM chorioretinal disorder appears to show many of the histopathologic features which characterize experimentally induced uveitis and other ocular diseases which may result from hypersensitivity to, or autoimmune reaction against, pigments of the uveal tract.
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Abstract
Vertebrate photoreceptors act as optical waveguides. They exhibit directionality, non-uniform distribution of energy within and immediately about the receptor, etc. Photolabile pigment absorption favors light traveling axially down the receptor. Clearly these properties influence response of the transducer. Retinal receptors, rods and cones, are aligned normally with a point approximating the center of the exit pupil of the eye. Taken together, these findings suggest that a prime role of receptor optics is to favor acceptance of the pertinent visual stimulus passing through the pupillary aperture and to inhibit stray light noise contained in the integrating sphere-like eyes. Many intriguing problems remain to be resolved. It is necessary to relate the properties of the receptor as a waveguide to determinations of directional sensitivity of the retina (Stiles-Crawford effects), and in particular, to understand mechanisms leading to fine receptor alignment. There must also be a pathology of receptor orientation--a science still in its infancy.
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Zyznar ES, Cross FB, Nicol JA. Uric acid in the tapetum lucidum of mooneyes Hiodon (Hiodontidae Teleostei). PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON. SERIES B, BIOLOGICAL SCIENCES 1978; 201:1-6. [PMID: 27789 DOI: 10.1098/rspb.1978.0029] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Tapeta lucida (ocular reflectors) of mooneyes,
Hiodon tergisus
and
H. alosoides
, lie in the pigment epithelium, the processes of which are packed with reflecting particles and also contain melanin granules. The reflecting particles are tiny birefringent crystals. On the basis of chromatography, u. v. spectroscopy and enzymic degradation (with uricase), it is concluded that the reflecting material contains uric acid. Mooneye tapeta are compared with those of other teleosts.
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