scholarly journals Ultrastructure within the Lateral Plexus of the Limulus Eye

1972 ◽  
Vol 59 (3) ◽  
pp. 285-304 ◽  
Author(s):  
Moshe Gur ◽  
Richard L. Purple ◽  
Russell Whitehead
Keyword(s):  
Lateral Inhibition ◽  
Serial Section ◽  
Compound Eye ◽  
Branching Pattern ◽  
Synaptic Contacts ◽  
Ribbon Synapses ◽  
Section Technique ◽  
Transmitter Substance ◽  
Horizontal Spread ◽  
Retinular Cells

The ultrastructure of the lateral plexus in the compound eye of Limulus is investigated by serial section technique. "Cores" of tissue containing the axons, lateral plexus, and neuropile associated with one sensory ommatidium show the following features: (a) collateral branches from retinular cells do not contribute to the lateral plexus proper, but do form retinular neuropile by contacting collaterals of a self-contained cluster of retinular axons; (b) collateral branches from eccentric cell axons always branch repeatedly upon leaving the parent axon, and compose the bulk of the lateral plexus; (c) the most distal collateral branches from an eccentric cell axon appear to form neuropile and synaptic contacts with each other, whereas more proximal branches form synaptic contacts with collaterals from eccentric cell axons of neighboring ommatidia. We conclude that the ribbon synapses and associated transmitter substance in eccentric cell collaterals must be inhibitory, and that two pathways for self-inhibition may exist. We suggest, as a working hypothesis for the structure of the lateral plexus, a branching pattern with depth that mirrors the horizontal spread of lateral inhibition measured physiologically.

Anatomical circuitry of lateral inhibition in the eye of the horseshoe crab, Limulus polyphemus

1985 ◽  
Vol 225 (1239) ◽  
pp. 219-249 ◽  
Keyword(s):  
Lateral Inhibition ◽  
Synaptic Input ◽  
Horseshoe Crab ◽  
Compound Eye ◽  
Synapse Formation ◽  
Signal Transmission ◽  
Intrinsic Property ◽  
Limulus Polyphemus ◽  
Inhibitory Synapses ◽  
Retinular Cells

Lengthy uninterrupted series of sections of the neural plexus in the compound eye of the horseshoe crab, Limulus polyphemus , have been used to reconstruct all the arborizations and their synaptic interconnections in a neuropil knot. This one microglomerulus contains the axons of 19 retinular cells, which pass by without contacts; 13 efferent fibres with 44 synapses to and from eccentric cell collaterals; and arborizations from 54 eccentric cells with 577 synapses. Eccentric cell axons are devoid of synaptic input. Their collaterals ramify in synaptic knots and subserve both pre- and postsynaptic functions simultaneously. Arborizations near the axon of origin have a highly branched pattern (up to 20 bifurcations), a high synaptic input:output ratio (up to about 9:1), and high synaptic density (a maximum of 12 per micrometre of neurite length). The opposite extreme is represented by sparsely branched eccentric cell collaterals distant from their axons of origin with very little synaptic input and sparse output. Spatially graded lateral inhibition is the apparent outcome of a radially decreasing distribution of inhibitory synapses on the arborizations of eccentric cell collaterals combined with possible decremental signal transmission in the plexus. The synaptic analysis has a bearing on most physiological aspects of lateral inhibition that have been studied in the Limulus eye. Implied in the results is the suggestion that synapse formation is an intrinsic property of the presynaptic element, but that the connectivity is governed by the electrical activity of target neurons.

Fine structure of the compound eye of the black fly Simulium vittatum (Diptera: Simuliidae)

1987 ◽  
Vol 65 (6) ◽  
pp. 1454-1469 ◽  
Author(s):  
Gail E. O'Grady ◽  
Susan B. McIver
Keyword(s):  
Fine Structure ◽  
Compound Eye ◽  
Sensory Receptor ◽  
Dorsal Region ◽  
Male And Female ◽  
Simulium Vittatum ◽  
Transmission Electron ◽  
Accessory Pigment ◽  
Open Rhabdom ◽  
Retinular Cells

The fine structure of the ommatidia in light- and dark-adapted eyes of male and female Simulium vittatum Zetterstedt was investigated using scanning and transmission electron microscopy. The male eye is divided into distinct dorsal and ventral regions. The facets in the dorsal region are approximately two times larger than those in the ventral one, which are similar in size to the ones in the female eye. All ommatidia of S. vittatum examined consist of two general regions: a distal dioptric apparatus with bordering primary and accessory pigment and Semper cells, and a sensory receptor layer. Each ommatidium in the female eye and ventral eye of the male has eight retinular cells (R cells): six peripheral (R1–6) and two central (R7, R8). R7 occurs distally and R8 basally. Strikingly, the ommatidia in the dorsal eye of the male lack the R7 cell. In all ommatidia, rhabdomeres on the inner surface of the peripheral R cells are separate throughout their length, creating an open rhabdom. A greater diameter of corneal facets, elongated peripheral R cells, and perhaps the lack of the R7 cell are specializations of the dorsal region of the eye that help the male to detect small, rapidly moving females against the skylight as they fly above the swarm of males. Differences observed between light- and dark-adapted eyes of male and female S. vittatum were the same and were associated with the internal components of the peripheral R cells.

Lateral Inhibition in the Com pound Eye of the Fly, Musca

1974 ◽  
Vol 29 (1-2) ◽  
pp. 95-97 ◽  
Author(s):  
K. Kirschfeld ◽  
B. Lutz
Keyword(s):  
Lateral Inhibition ◽  
Compound Eye ◽  
Common Phenomenon ◽  
Inhibitory Interactions

Abstract Lateral Inhibition, Compound Eye, Fly Lateral inhibition is a common phenomenon in the eyes of vertebrates as well as of invertebrates. Indications of lateral inhibitory interactions in dipteran eyes have been found by means of electro-physiological techniques*' 2. It was not possible,

Two opsins from the compound eye of the crab Hemigrapsus sanguineus

1996 ◽  
Vol 199 (2) ◽  
pp. 441-450 ◽  
Author(s):  
K Sakamoto ◽  
O Hisatomi ◽  
F Tokunaga ◽  
E Eguchi
Keyword(s):  
Photoreceptor Cell ◽  
Compound Eye ◽  
Visual Pigments ◽  
Amino Acid Residues ◽  
Hemigrapsus Sanguineus ◽  
Brachyuran Crab ◽  
Maximal Absorption ◽  
Retinular Cells ◽  
Cdna Nucleotide

The primary structures of two opsins from the brachyuran crab Hemigrapsus sanguineus were deduced from the cDNA nucleotide sequences. Both deduced proteins were composed of 377 amino acid residues and included residues highly conserved in visual pigments of other species, and the proteins were 75 % identical to each other. The distribution of opsin transcripts in the compound eye, determined by in situ hybridization, suggested that the mRNAs of the two opsins were expressed simultaneously in all of the seven retinular cells (R1-R7) forming the main rhabdom in each ommatidium. Two different visual pigments may be present in one photoreceptor cell in this brachyuran crab. The spectral sensitivity of the compound eye was also determined by recording the electroretinogram. The compound eye was maximally sensitive at about 480 nm. These and previous findings suggest that both opsins of this brachyuran crab produce visual pigments with maximal absorption in the blue-green region of the spectrum. Evidence is presented that crustaceans possess multiple pigment systems for vision.

Packaging of rhodopsin and porphyropsin in the compound eye of the crayfish

1993 ◽  
Vol 10 (2) ◽  
pp. 193-202 ◽  
Author(s):  
Joel Zeiger ◽  
Timothy H. Goldsmith
Keyword(s):  
Visual Pigment ◽  
Regional Variation ◽  
Compound Eye ◽  
Procambarus Clarkii ◽  
Difference Spectra ◽  
Retinular Cells ◽  
Different Levels

AbstractThe distribution of 3-dehydroretinal (Ral2) in dorsal, middle, and ventral slices of eyes of the crayfish Procambarus clarkii was examined by HPLC. No pronounced differences were found. Similar results were obtained when the eyes were cut into anterior, intermediate, and posterior portions.Dichroic difference spectra were measured in single halves of microvillar layers of isolated rhabdoms and the proportions of rhodopsin (P1) and porphyropsin (P2) estimated by comparison with computer-generated mixtures of these pigments, whose spectra are known from previous work. The fraction of visual pigment that is porphyropsin appears to be uniform throughout individual retinular cells and among the retinular cells of individual rhabdoms, but various substantially among different rhabdoms from the same eye.The interommatidial variation in the amount of P2 greatly exceeds the gross regional variation in Ral2. This means there is an intermingling of ommatidia with different levels of P2. The variability in P2 among ommatidia is not likely to have important implications for the vision of the crayfish but suggests that in the metabolism of retinoids, individual ommatidia are quasi-independent metabolic units. The results are compatible with a single opsin for both crayfish rhodopsin and porphyropsin.

scholarly journals Some aspects of vision in the lobster, Homarus vulgaris, in relation to the structure of its eye

1963 ◽  
Vol 43 (3) ◽  
pp. 683-699 ◽  
Author(s):  
Elizabeth M. Kampa ◽  
Bernard C. Abbott ◽  
Brian P. Boden
Keyword(s):  
Compound Eye ◽  
Crystalline Cone ◽  
Cone Cells ◽  
Retinular Cells

The compound eye of the lobster H. vulgaris has a single lobe; its ommatidia are uniform except in length. Each ommatidium consists of a corneal facet, two corneagenous cells, four cone cells, a four-part crystalline cone, an elongate cone stalk, seven retinular cells and a four-part rhabdom. Growth between the zoaeal and adult stages is primarily a lengthening of the cone stalk.

scholarly journals Regionalization in the compound eye of Talitrus saltator (Crustacea, Amphipoda)

2019 ◽  
Author(s):  
Alice Ciofini ◽  
Luca Mercatelli ◽  
Yumi Yamahama ◽  
Takahiko Hariyama ◽  
Alberto Ugolini
Keyword(s):  
Compound Eye ◽  
Wavelength Region ◽  
Ventral Part ◽  
Dorsal Part ◽  
Blue Filter ◽  
Talitrus Saltator ◽  
Summary Statement ◽  
Celestial Compass ◽  
Behavioural Experiments ◽  
Retinular Cells

AbstractThe crustacean Talitrus saltator is known to use many celestial cues during its orientation along the sea-land axis of sandy shores. In this paper, we investigated the existence of the eye regionalization by morphological, electrophysiological and behavioural experiments. Each ommatidium possesses five radially arranged retinular cells producing a square fused rhabdom by R1-R4 cells; the smaller R5 exist between R1 and R4. The size of R5 rhabdomere is largest in dorsal part and becomes gradually smaller in median and ventral part of the eye. Spectral-sensitivity measurements were recorded from either dorsal or ventral parts of the compound eye to clarify the chromatic difference. Results show that the dorsal part is green and UV-blue dichromatic, whereas the ventral part is UV (390 nm) with a substantial population of 450 nm receptors with the responses in the longer wavelength region. To evaluate the orienting behaviour of individuals, their eyes were black painted either in the dorsal or ventral part, under natural sky or a blue filter with or without the vision of the sun. Results show that animals painted on the dorsal part of their eyes tested under the screened sun were more dispersed and in certain cases their directions deflected than other groups of individuals. Furthermore, sandhoppers subjected to the obscuring of this area met in any case high difficulties in their directional choices. Therefore, our present work indicates the existence of a regionalization of the compound eye of T. saltator.Summary statementThis work provides evidences of the morphological and electrophysiological regionalization of the compound eye and the visual capabilities for behaviour involved in the recognition of the celestial compass orienting factors in crustaceans.

Histochemical localization of acetylcholinesterase in the lateral eye and brain of Limulus polyphemus: Might acetylcholine be a neurotransmitter for lateral inhibition in the lateral eye?

1994 ◽  
Vol 11 (5) ◽  
pp. 989-1001 ◽  
Author(s):  
Eric P. Hornstein ◽  
Daniel L. Sambursky ◽  
Steven C. Chamberlain
Keyword(s):  
Optic Nerve ◽  
Lateral Inhibition ◽  
Horseshoe Crab ◽  
Compound Eye ◽  
Nerve Fibers ◽  
Intense Staining ◽  
Histaminergic Neurons ◽  
Lateral Eye ◽  
Weak Staining ◽  
The Brain

AbstractThe distribution of acetylcholinesterase (AChE) in the lateral eye and brain of the horseshoe crab was investigated with histochemical means using standard controls to eliminate butyrylcholinesterase and nonspecific staining. Intense staining was observed in the neural plexus of the lateral compound eye, in the lateral optic nerve, and in various neuropils of the brain. Nerve fibers with moderate to weak staining were widespread in the brain. No sornata were stained in either the lateral eye or the brain. The distribution of acetylcholinesterase in the supraesophageal ganglia and nerves of the giant barnacle was also investigated for comparison. Although both the median optic nerve of the barnacle and the lateral optic nerve of the horseshoe crab appear to contain the fibers of histaminergic neurons, only the lateral optic nerve of the horseshoe crab shows AChE staining. Other parts of the barnacle nervous system, however, showed intense AChE staining. These results along with the histochemical controls eliminate the possibility that some molecule found in histaminergic neurons accounted for the AChE staining but support the possibility that acetylcholine might be involved as a neurotransmitter in lateral inhibition in the horseshoe crab retina. Two reasonable neurotransmitter candidates for lateral inhibition, histamine and acetylcholine, must now be investigated.

scholarly journals FINE STRUCTURE OF THE RETINULAE IN THE COMPOUND EYE OF THE HONEY-BEE

1962 ◽  
Vol 14 (3) ◽  
pp. 489-494 ◽  
Author(s):  
Timothy H. Goldsmith
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Electron Microscope ◽  
Honey Bee ◽  
Cross Sections ◽  
Compound Eye ◽  
Parallel Array ◽  
Retinular Cells

The retinula of the compound eye of the worker honey-bee has been examined with the electron microscope. The rhabdom lies on the ommatidial axis; it is usually cylindrical in shape, about 3 to 4 µ in diameter, and lacks an axial cavity. Cross-sections show it to be four parted, although it is formed from eight retinular cells (Figs. 2, 3). Each quadrant of the rhabdom consists of a closely packed parallel array of tubules with long axes perpendicular to the axis of the rhabdom. The tubules in adjacent quadrants of the rhabdom are mutually perpendicular. At the distal end of the ommatidium these tubules are seen to be microvilli of the retinular cells. Immediately surrounding the rhabdom, the cytoplasm of the retinular cells contains a membranous endoplasmic reticulum which is oriented approximately radially with respect to the axis of the ommatidium. Farther away from the rhabdom the cytoplasm contains numerous mitochondria.

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