Synaptic organization of two types of amacrine cells with CRF-like immunoreactivity in the turtle retina

1991 ◽  
Vol 6 (3) ◽  
pp. 257-269 ◽  
Author(s):  
Douglas E. Williamson ◽  
William D. Eldred
Keyword(s):  
B Cells ◽  
Plexiform Layer ◽  
Amacrine Cells ◽  
Type A ◽  
Inner Plexiform Layer ◽  
Synaptic Organization ◽  
Type B ◽  
Synaptic Contacts ◽  
A Cells ◽  
Visual Streak

AbstractThe ultrastructural features and synaptic contacts of two amacrine cell types with corticotropin-releasing factor-like immunoreactivity in the turtle retina were examined using electron immunocytochemistry. Type A cells were found only in the visual streak and had elongated dendritic arborizations that ran parallel to the visual streak. These cells arborized primarily in stratum 1 and near the border of strata 2 and 3 of the inner plexiform layer, with some processes extending into stratum 5. Type B cells were found only ventral to the visual streak and arborized primarily in a wide band in strata 4 and 5, with sparse dendritic arborizations in stratum 1.There was a diffuse cytoplasmic reaction product within each cell type; however, large labeled vesicles were rarely observed. Type A amacrine cells received many conventional synaptic contacts from amacrine cells in stratum 1 and at the border of strata 2 and 3, but only a small number of contacts in stratum 5. Bipolar synaptic contacts onto type A amacrine cells were observed in strata 1 and at the border of strata 2 and 3. The only positively identified synaptic outputs of type A cells were conventional synapses onto amacrine cells in strata 1 and at the border of 2 and 3. Type B amacrine cells received synaptic contacts from amacrine cells in strata 1 and 5, and bipolar cell synaptic input in stratum 5. They made conventional synapses onto amacrine cells in strata 1 and 5, and onto bipolar cells in stratum 5. We also found conventional synaptic contacts between unlabeled amacrine cells and type B amacrine cells outside of the primary layers of stratification. In addition, there were specialized junctions observed between type A cell profiles in stratum 1 and between type B cell profiles in stratum 5. The unique regional distributions of the type A and B cells, as well as their differences in synaptic connectivity, suggested that these amacrine cells play distinct physiological roles although they contain the same neuropeptide.

Synaptic organization of the frog retina: an electron microscopic analysis comparing the retinas of frogs and primates

1968 ◽  
Vol 170 (1019) ◽  
pp. 205-228 ◽  
Keyword(s):  
Synaptic Vesicles ◽  
Synaptic Contact ◽  
Plexiform Layer ◽  
Amacrine Cells ◽  
Outer Plexiform Layer ◽  
Inner Plexiform Layer ◽  
Synaptic Organization ◽  
Synaptic Contacts ◽  
Frog Retina ◽  
Cell Processes

The synaptic contacts in the inner and outer plexiform layers of the frog retina have been identified and studied by electron microscopy. In the inner plexiform layer, two types of synaptic contact were recognized. One type, believed to be the synaptic contact of the bipolar terminals, is characterized by a synaptic ribbon in the presynaptic cytoplasm. At such ribbon contacts, there are ordinarily two postsynaptic elements, both of which usually contain numerous synaptic vesicles and appear morphologically identical. The second type of synaptic contact in the inner plexiform layer has a more conventional morpho­logy and is observed very much more frequently than are the ribbon contacts. It is characterized by a dense aggregation of synaptic vesicles clustered close to the presynaptic membrane and is thought to be the synaptic contact of the amacrine processes. The conventional synapses are presynaptic to ribbon-containing processes, ganglion cell dendrites, and other amacrine cell processes. Reciprocal contacts between processes making ribbon synapses, and processes making conventional synapses are often observed. Serial synapses between morphologically identical processes, presumably amacrine processes, are frequently seen; and up to four synapses in series between five adjacent processes have been observed. These findings suggest that in the inner plexiform layer of the frog: (1) bipolar terminals synapse primarily with amacrine processes; (2) amacrine processes synapse extensively with the processes of other amacrine cells; and (3) ganglion cells are driven primarily by the amacrine cells. In the outer plexiform layer, processes penetrate into invaginations in the bases of the receptor terminals and lie in close proximity to the synaptic ribbons of the terminals, where the processes presumably receive synaptic input from the receptors. Elsewhere in the outer plexiform layer, knob-like processes, probably from horizontal cells, make conventional synaptic contacts with other horizontal cell processes and probably with bipolar dendrites.

Morphology and distribution of serotonin-like immunoreactive amacrine cells in the retina of Bufo marinus

1990 ◽  
Vol 5 (04) ◽  
pp. 371-378 ◽  
Author(s):  
Baosong Zhu ◽  
Charles Straznicky
Keyword(s):  
Nearest Neighbor ◽  
Linear Regression Analysis ◽  
Plexiform Layer ◽  
Great Majority ◽  
Amacrine Cells ◽  
Type A ◽  
Large Cell ◽  
Cell Types ◽  
Bufo Marinus ◽  
Inner Plexiform Layer

AbstractUsing an antibody against serotonin (5-hydroxytryptamine, 5-HT), serotonin-like immunoreactive (serotonin IR) neurons were demonstrated in the retina of adultBufo marinus. All immunoreactive neurons were identified as amacrine cells (ACs). The dendrites of serotonin-IR ACs branched diffusely and densely throughout all levels of the inner plexiform layer (IPL) of the retina. The great majority of these cell somata were located in the vitread part of the inner nuclear layer (INL) and a few of them (ranging from 9–29 cells) were displaced into the ganglion cell layer (GCL). On the basis of the soma sizes, two populations of serotonin-IR ACs, large (type A) and small (type B), were distinguished. 6-Hydroxydopamine (6-OHDA) injected into the eye abolished immunoreactivity in the recently reported tyrosine hydroxylase (TH)-IR ACs (Zhu & Straznicky, 1990), whereas serotonin-IR ACs remained unaffected.The number of serotonin-IR cells per retina ranged from 23,750–27,390, with a ratio of 1:1.6 to 1:1.9 between type A and B cells. Both cell types were distributed nonuniformly across the retina. Cell densities were slightly lower in the peripheral (96 cells/mm2) than in the central (164 cells/mm2) retina. Linear regression analysis confirmed the presence of a decreasing density gradient from the retinal center to the retinal margin for both small and large cell types. The analysis of the nearest neighbor distances showed that the retinal distribution of serotonin-IR ACs was orderly.These results have been taken to indicate that 5-HT-IR cells correspond to a population of serotonincontaining ACs. It is suggested that dopamine and serotonin are contained in two different populations of ACs in the rtina ofBufo marinus.

The type 1 polyaxonal amacrine cells of the rabbit retina: A tracer-coupling study

2004 ◽  
Vol 21 (2) ◽  
pp. 145-155 ◽  
Author(s):  
LAYNE L. WRIGHT ◽  
DAVID I. VANEY
Keyword(s):  
Dendritic Tree ◽  
Plexiform Layer ◽  
Amacrine Cells ◽  
Field Size ◽  
Equivalent Diameter ◽  
Inner Plexiform Layer ◽  
Rabbit Retina ◽  
Visual Streak ◽  
Field Area

The type 1 polyaxonal (PA1) cell is a distinct type of axon-bearing amacrine cell whose soma commonly occupies an interstitial position in the inner plexiform layer; the proximal branches of the sparse dendritic tree produce 1–4 axon-like processes, which form an extensive axonal arbor that is concentric with the smaller dendritic tree (Dacey, 1989; Famiglietti, 1992a,b). In this study, intracellular injections of Neurobiotin have revealed the complete dendritic and axonal morphology of the PA1 cells in the rabbit retina, as well as labeling the local array of PA1 cells through homologous tracer coupling. The dendritic-field area of the PA1 cells increased from a minimum of 0.15 mm2 (0.44-mm equivalent diameter) on the visual streak to a maximum of 0.67 mm2 (0.92-mm diameter) in the far periphery; the axonal-field area also showed a 3-fold variation across the retina, ranging from 3.1 mm2 (2.0-mm diameter) to 10.2 mm2 (3.6-mm diameter). The increase in dendritic- and axonal-field size was accompanied by a reduction in cell density, from 60 cells/mm2 in the visual streak to 20 cells/mm2 in the far periphery, so that the PA1 cells showed a 12 times overlap of their dendritic fields across the retina and a 200–300 times overlap of their axonal fields. Consequently, the axonal plexus was much denser than the dendritic plexus, with each square millimeter of retina containing ∼100 mm of dendrites and ∼1000 mm of axonal processes. The strong homologous tracer coupling revealed that ∼45% of the PA1 somata were located in the inner nuclear layer, ∼50% in the inner plexiform layer, and ∼5% in the ganglion cell layer. In addition, the Neurobiotin-injected PA1 cells sometimes showed clear heterologous tracer coupling to a regular array of small ganglion cells, which were present at half the density of the PA1 cells. The PA1 cells were also shown to contain elevated levels of γ-aminobutyric acid (GABA), like other axon-bearing amacrine cells.

Loss of hamster Leydig cells during regression after exposure to a short photoperiod

2018 ◽  
Vol 30 (8) ◽  
pp. 1137 ◽  
Author(s):  
E. Beltrán-Frutos ◽  
V. Seco-Rovira ◽  
J. Martínez-Hernández ◽  
C. Ferrer ◽  
L. M. Pastor
Keyword(s):  
B Cells ◽  
Leydig Cells ◽  
Light And Electron Microscopy ◽  
Type A ◽  
Nuclear Antigen ◽  
Control Group ◽  
C Cells ◽  
Type B ◽  
A Cells ◽  
Type C

The aim of the present study was to evaluate the changes that occur in hamster Leydig cells during regression. Animals were divided into control, mild regression (MR), strong regression (SR) and total regression (TR) groups. Leydig cells were characterised by light and electron microscopy. Terminal deoxyribonucleotidyl transferase-mediated dUTP–digoxigenin nick end-labelling (TUNEL) and proliferating cell nuclear antigen (PCNA) antibodies were used to detect apoptosis and proliferation respectively. Three types of Leydig cells (A, B and C) could be differentiated. Type A cells were small in size compared with Leydig cells from animals exposed to a long photoperiod, which was a result of a decreased cytoplasm and nucleus. Type B cells were even smaller than Type A cells in regression groups. Type C exhibited cytoplasm vacuolisation. The percentage of Type C cells from the control group was much lower than in the MR, SR and TR groups. (P < 0.05). In the SR and TR groups, there was a significant decrease in the percentage of Type B cells compared with the control and MR groups (P < 0.05). The total number of Leydig cells decreased during testicular regression (P < 0.05). The total number of Type A and B cells was significantly lower in the MR, SR and TR groups compared with the control group (P < 0.05). There were no significant differences in the proliferation and apoptosis index in the groups studied. The findings of the present study indicate that there are three types of Leydig cells (A, B and C) in all hamsters studied and that regression causes an increase in the number of Type C cells, so that the reduction in the number Leydig cells during the phases of regression studied must be the result of necrosis and/or necroptosis.

Morphology of the “Sulphur Granules” (Drusen) in Some Actinomycotic Infections. A Light and Electron Microscopic Study

1978 ◽  
Vol 15 (4) ◽  
pp. 506-518 ◽  
Author(s):  
G. Bestetti
Keyword(s):  
Cell Wall ◽  
B Cells ◽  
Amorphous Material ◽  
Light And Electron Microscopy ◽  
Type A ◽  
Cross Wall ◽  
Type B ◽  
Electron Microscopic ◽  
A Cells ◽  
Cellular Wall

The granules (Drusen) within the inflammatory lesions in three cases of infection by Actinomyeetales were studied with light and electron microscopy. The material consisted of subcutaneous granulomas caused by Actinomyces bovis in a cow, epidural granulomas caused by A. viscosus in the spinal canal of a cat and cerebral granulomas caused by Nocardia in a dog. The granules of A. bovis were 2000 to 3000 micrometers in diameter. Their centers consisted of a slightly basophilic, gram- and grocott-negative material with branching, gram-and grocott-positive filaments. The periphery was slightly basophilic or eosinophilic, but gram- and grocott-positive. Its surface was made of clubs (15 × 3.5 micrometers); they were acidophilic, gram- and grocott-negative. In the center of the granule there are numerous type a cells (coccobacillary cells with a trilaminar cell wall of 12 nanometers) and rarely type b cells (filaments with bilaminar cell wall of 30 nanometers). The periphery was made of germinative centers of type a cells. The clubs were lytic type b cells, embedded in an amorphous material. The granules (Drusen) of A. viscosus were 200 to 600 micrometers in diameter. Their center was slightly eosinophilic, gram- and grocott-negative and contained gram- and grocott-positive filaments. Their periphery was basophilic and contained alternating gram-and grocott-negative areas and radial gram- and grocott-positive filaments. There were no clubs. In the center there were type b cells (filaments with a trilaminar cellular wall of 30 nanometers). The periphery was made of germinative centers of type a cells (coccobacillary with a trilaminar cell wall of 10 to 11 nanometers). The germinative centers were separated from each other by radial bundles of type b cells. The granules (Drusen) of Nocardia were acidophilic, gram- and grocott-positive and surrounded by 1.8 × 0.5-micrometer clubs that were acidophilic, gram- and grocott-negative. There were type a cells (filamentous to bacillary with monolaminar cell wall of 19 nanometers and cross wall) and type b cells (filamentous to bacillary with monolaminar cell wall of 65 nanometers and without cross wall). The remarkable morphological differences of the three species of Actinomycetales are specific, independent from host and type of tissue, and therefore reliable for diagnostic purposes.

Synaptic organization of GABAergic amacrine cells in the salamander retina

2004 ◽  
Vol 21 (6) ◽  
pp. 817-825 ◽  
Author(s):  
JUN ZHANG ◽  
HO-HWA WANG ◽  
CHEN-YU YANG
Keyword(s):  
Amacrine Cell ◽  
Plexiform Layer ◽  
Amacrine Cells ◽  
Bipolar Cells ◽  
Inner Plexiform Layer ◽  
Synaptic Organization ◽  
Proximal Margin ◽  
Functional Roles ◽  
Small Peak ◽  
Immuno Electron Microscopy

The synaptic organization of GABA-immunoreactive (GABA-IR) amacrine cells in the inner plexiform layer (IPL) of salamander retina was studied with the use of postembedding immuno-electron microscopy. A total of 457 GABA-IR amacrine synapses, with identified postsynaptic elements, were analyzed on photomontages of electron micrographs covering 3,618 μm2 of the IPL. GABA-IR amacrine synapses were distributed throughout the IPL, with a small peak at the proximal margin of sublamina a. The majority of the output targets (81%) were GABA(−) neurons. Most of the contacts were simple synapses with one postsynaptic element identified as a process of an amacrine cell (55%), bipolar cell (19%) or ganglion cell (26%), and serial synapses were very rare. Of the 89 postsynaptic bipolar terminals, 63% participated in a reciprocal feedback synapse with the same presynaptic GABA-IR amacrine profile. There appeared to be no preference between GABA-IR amacrine contacts with rod- or cone-dominated bipolar cells (9.1% vs. 8.9%) or in the total number of amacrine synapses in sublaminas a and b (52% vs. 47%). The preponderance of amacrine cell input to bipolar cells in the OFF layer was derived from GABA-IR cells. These findings provide ultrastructural support to the existing physiological studies regarding the functional roles of the GABAergic amacrine cells in this species. Our results have added to the data base demonstrating that, in contrast to mammals, GABA-IR amacrine cells in amphibians and other nonmammals contact other amacrine cells more frequently, suggesting greater involvement of GABAergic amacrine cells in modulating lateral inhibitory pathways.

Phrenic motoneurons in the cat: subpopulations and nature of respiratory drive potentials

1979 ◽  
Vol 42 (1) ◽  
pp. 76-90 ◽  
Author(s):  
A. J. Berger
Keyword(s):  
Membrane Potential ◽  
B Cells ◽  
Input Resistance ◽  
Type A ◽  
Current Injection ◽  
Type B ◽  
Expiratory Phase ◽  
Axonal Conduction ◽  
Phrenic Motoneurons ◽  
A Cells

1. Intracellular recordings were made from 78 phrenic motoneurons (PM) in anesthetized, paralyzed, artificially ventilated cats that were slightly hypercapnic. 2. Three subpopulations of PM (types A, B, and A/B) were identified on the basis of their membrane potential trajectories during expiration (E). Type A cells exhibited wholly linear trajectories. These were rapidly hyperpolarized at the onset of E followed by a slow ramp of increasing hyperpolarization observed in 51 of 59 type A cells. Types B (13 cells) and A/B (6 cells) had nonlinear trajectories in E. Type B cells approached their end-expiratory potential levels more slowly. 3. Measurements of axonal conduction velocity, expiratory phase input resistance, initial depolarization rate, and initial spike onset during inspiration revealed that type B cells had significantly slower axonal conduction velocities, higher input resistances, greater initial depolarization rates, and earlier initial spike onsets than type A cells. The properties of type A/B were intermediate between the other cell types. These results support the hypothesis that the PM pool is not homogeneous. 4. Active E-phase inhibition of all types of PM was directly demonstrated by reversal of the increasing hyperpolarizing wave to a depolarizing wave with hyperpolarizing current injection using a bridge circuit. Thus hyperpolarization of PM during E is not merely due to a central disfacilitation. 5. During hyperpolarizing current injection the inspiratory phase membrane potential trajectory of all PM became a ramp depolarization similar to that seen during control conditions in type A cells. These results support the conclusion that all cells within the PM pool are receiving a similar central excitatory synaptic input during inspiration. The rapid initial depolarization of type B and their concomitant early spike onset is a consequence in part of a rebound excitation from their expiratory phase inhibition as well as a higher input resistance, probably due to a smaller cell size. 6. Expiratory related neural activity was recorded within the phrenic motor nucleus. It is suggested that these expiratory related neural elements, based on the temporal pattern of their activity, may be responsible for the active inhibition of PM.

Synaptic organization of dopaminergic interplexiform cells in the goldfish retina

1988 ◽  
Vol 1 (1) ◽  
pp. 13-29 ◽  
Author(s):  
Stephen Yazulla ◽  
Charles L. Zucker
Keyword(s):  
Ganglion Cell ◽  
Plexiform Layer ◽  
Amacrine Cells ◽  
Bipolar Cells ◽  
Gaba Uptake ◽  
Inner Plexiform Layer ◽  
Synaptic Organization ◽  
Input And Output ◽  
Chemical Synapses ◽  
Goldfish Retina

AbstractThe synaptic organization of dopaminergic interplexiform cells (DA-IPC) in the goldfish retina was studied by a combined double-label electron-microscopical (EM) immunocytochemical/autoradiographical study. DA-IPCs were labeled with antisera against tyrosine hydroxylase. The possibility of synaptic contact with GABAergic amacrine cells in the proximal inner plexiform layer (IPL) was studied by using 3H-GABA uptake. Most synaptic input and output from DA-IPC processes involved amacrine cell processes. In addition, synaptic interactions were observed between DA-IPC processes and bipolar cell terminals, other DA-IPC processes, very small dendrites in the IPL, ganglion cell and optic fiber layers (OFL), and cell bodies in the ganglion cell layer (GCL). Input and output synapses with GABAergic amacrine processes also were observed. Two-thirds of the DA-IPC boutons in the proximal IPL were involved in “junctional appositions,” that is, the junctions appeared to be specialized but they were different than classical chemical synapses. The synaptic organization of DA-IPCs in the goldfish IPL appears to be far more complex than previously thought. Although earlier studies have attempted to explain the action of dopamine in terms of interaction only with amacrine cells, the present study shows that effects involving bipolar cells, other DA-IPCs, unidentified processes and cell bodies in the GCL and OFL must be considered as well.

The morphology of the bipolar cells, amacrine cells and ganglion cells in the retina of the turtle Pseudemys Scripta Elegans

1982 ◽  
Vol 298 (1092) ◽  
pp. 355-393 ◽  
Keyword(s):  
Ganglion Cells ◽  
Dendritic Tree ◽  
Plexiform Layer ◽  
Amacrine Cells ◽  
Dendritic Morphology ◽  
Bipolar Cells ◽  
Inner Plexiform Layer ◽  
Visual Streak ◽  
Pseudemys Scripta ◽  
Oriented Parallel

The morphology of the neurons that contribute to the inner plexiform layer of the retina of the turtle Pseudemys scripta elegans has been studied by light microscopy of whole-mount material stained by the method of Golgi. Cells have been distinguished on the basis of criteria that include dendritic branching patterns, dendritic morphology, dendritic tree sizes and stratification of processes in the inner plexiform layer. Many of the neurons have dendritic trees oriented parallel to and a few exhibit an orthogonal orientation with the linear visual streak present in the retina of this species. The neurons of the turtle retina have been compared, where possible, with the neurons of the lizard retina as described by Cajal. The findings are discussed in relation to other vertebrate retinas, and correlations are made with recent electrophysiological recordings of the turtle retina. Comments are made with regard to the significance of orientation of neurons relative to the linear visual streak.

Immunocytochemical response of type A and type B intercalated cells to increased sodium chloride delivery

1992 ◽  
Vol 262 (2) ◽  
pp. F288-F302 ◽  
Author(s):  
J. Kim ◽  
W. J. Welch ◽  
J. K. Cannon ◽  
C. C. Tisher ◽  
K. M. Madsen
Keyword(s):  
Sodium Chloride ◽  
B Cells ◽  
Type A ◽  
Band 3 ◽  
Intercalated Cells ◽  
Band 3 Protein ◽  
Type B ◽  
Membrane Area ◽  
A Cells ◽  
Chronic Infusion

Two populations of intercalated cells, type A and type B, are present in the rat cortical collecting duct (CCD). Type A cells are involved in proton secretion and contain an apical H(+)-adenosinetriphosphatase (ATPase) and a basolateral Cl(-)-HCO3- exchanger. Type B cells are believed to be involved in HCO3- secretion, which is mediated by a Cl(-)-HCO3- exchange process and is Cl- dependent. The aim of this study was to examine the morphological and immunocytochemical response of type B intercalated cells in the rat to increased delivery of Cl- to the CCD. This was accomplished by chronic infusion of a loop diuretic, bumetanide (30 mg.kg body wt-1.day-1), via an osmotic minipump, and simultaneous administration of 0.9% sodium chloride in the drinking water for 6 days. The kidneys were preserved by in vivo perfusion with a periodate-lysine-paraformaldehyde fixative and processed for horseradish peroxidase and protein A gold immunocytochemistry, using rabbit polyclonal antibodies against carbonic anhydrase II, proton ATPase, and band 3 protein. Chronic infusion of bumetanide in combination with a high salt intake was associated with significant changes in the intercalated cells. Type B cells were increased in size and exhibited numerous apical microvilli, increased basolateral membrane area, and marked cytoplasmic and basolateral labeling for H(+)-ATPase. In contrast, type A cells were small and had sparse apical microprojections. H(+)-ATPase immunolabeling was observed primarily over apical tubulovesicles, and there was decreased basolateral immunolabeling for band 3 protein and occasional labeling for band 3 in lysosome-like structures. These observations support the hypothesis that increased delivery of Cl- to the CCD is associated with stimulation of type B intercalated cells to secrete HCO3-. The observations in type A cells are consistent with the cells being in a resting or inactivated state.

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