Terminations of photoreceptor axons from different regions of the compound eye of the desert ant Cataglyphis bicolor

1986 ◽  
Vol 228 (1250) ◽  
pp. 59-69 ◽  
Keyword(s):  
Electron Microscopy ◽  
Compound Eye ◽  
Second Order ◽  
The Other ◽  
Regional Specialization ◽  
Desert Ant ◽  
Monopolar Cell ◽  
New Type ◽  
Dorsal Retina ◽  
Cataglyphis Bicolor

The morphology of the photoreceptors from different regions of the desert an t’s compound eye is investigated by Golgi-impregnations and anterograde or retrograde haem peptide filling, combined with electron microscopy. A new type of receptor axon is described. This receptor is of the short (svf) type but terminates in the proximal layer of the lamina (epl-C), in contrast to the other short visual fibres, which terminate in the distal layer (epl-A) : Golgi-EM investigations show that this receptor axon belongs to the small photoreceptor R9. The receptor R9 appears to be pre- and postsynaptic to other receptor axons and to second order neurons. In each ommatidium, the axons of the two long photoreceptors (lvf) R1 and R5 (probably uv-receptors) remain paired down to their terminations in the distal layer of the medulla. The regional specialization of the retina (dorsal rim area (dra), dorsal retina (dr) and ventral retina (vr)) is reflected by the morphology of the receptor terminals and the second order neurons. The lamina underlying the dra consists of only one layer, an extended epl-A; in the remainder of the eye, the lamina is trilateral. In the dra all short visual fibres (svf) are equal in length. The extension of the monopolar cell dendrites is restricted to one cartridge only. In the medulla, the terminals of the lvfs deriving from the dra (R1 and R5) have more extensive arborizations than elsewhere in the eye.

Regional specialization in the eye of the sphingid moth Manduca sexta: Blue sensitivity of the ventral retina

1997 ◽  
Vol 14 (3) ◽  
pp. 523-526 ◽  
Author(s):  
Ruth R. Bennett ◽  
Richard H. White ◽  
Jeffery Meadows
Keyword(s):  
Manduca Sexta ◽  
Spectral Sensitivity ◽  
Compound Eye ◽  
Regional Specialization ◽  
Relative Contribution ◽  
Flower Visitation ◽  
Nectar Feeding ◽  
Sensitivity Curves ◽  
Receptor Mosaic ◽  
Dorsal Retina

AbstractThe compound eye of the tobacco hornworm moth Manduca sexta contains green-, blue-, and ultraviolet-sensitive photoreceptors. Electroretinogram spectral-sensitivity measurements were recorded from different regions of the retina in order to broadly map the distribution of the three receptor types. The relative contribution of the three receptors to spectral-sensitivity curves was estimated by fitting theoretical curves based on the absorption spectra of the three rhodopsins. This analysis indicated that the dorsal retina is green and ultraviolet dichromatic, with green-sensitive cells greatly predominating. The ventral retina is trichromatic with a substantial population of blue- and ultraviolet-sensitive receptors. We previously showed that flower visitation for nectar feeding is mediated mainly by blue-sensitive cells. Their localization in the ventral retina seems an appropriate adaptation of the receptor mosaic, since the moths hover above flowers as they feed.

The lamina monopolar cells in the optic lobe of the dragonfly sympetrum

1982 ◽  
Vol 297 (1084) ◽  
pp. 27-49 ◽  
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Optic Lobe ◽  
The Other ◽  
Cell Type ◽  
Other Hand ◽  
Monopolar Cell ◽  
Receptor Input ◽  
Serial Electron Microscopy

The connectivities of five monopolar cells, M I-M V, within the ventral cartridge of the lamina of the dragonfly Sympetrum have been analysed from serial electron microscopy and their morphologies confirmed from Golgi-electron microscopy. The results of synaptic analyses are presented from a single cartridge photographed in its entirety in one series of transverse sections through the complete depth of the lamina and corroborated from shorter series of sections of additional cartridges. Each monopolar cell is defined by and identified from the location of its soma and the characteristic position of its axon in the cartridge cross section. M I and M II are two axial monopolar cells with large-calibre axons, while axons of M III-M V are slender and occupy polar positions, M III and M IV next to M I, M V next to the long visual fibres R 6 and R 7. M I and M II contribute postsynaptically at the triad synapses of all six retinular terminals, M I contributing exclusively at its dendrites, which number about 50 % more than those of M II. The distribution of M I and M II dendrites in general reflects the geometry and extent of synaptic engagement with the surrounding retinular terminals. In addition M II is postsynaptic at synapses of the long visual fibres R 6 and R 7, thus receiving a comprehensive and exclusive receptor input; it is only postsynaptic in the lamina. M I, on the other hand, forms an output back upon certain of its retinular inputs and upon M IV. M III too forms an important output upon M IV and it receives a selective retinular input from R 1 at synapses that are the focus of an unexpected asymmetry within the cartridge. M V, like M III, receives a selective retinular input (from R 7) while M IV receives its retinular input only indirectly, from both M I and M III. M IV and M V, like M II, have no output within the lamina. Finally, all monopolar cells excluding M II receive input from an unidentified cell type or types, called a, an input that for M I and M III is reciprocal. To judge from the diversity of their synaptic configurations, the numbers of their dendrites and probably the numbers of their synapses too, the monopolar cells form a sequence in ascending richness M V -M I. Definite parallels exist between, respectively, M I and M II of Sympetrum and L 2 and L 1 of Musca and Apis and between M III of Sympetrum and L 3 of Apis ,but further homologies are unclear

Development of 200 kV Scanning-Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 410-411
Author(s):  
H. Koike ◽  
S. Sakurai ◽  
K. Ueno ◽  
M. Watanabe
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Scanning Transmission Electron Microscope ◽  
The Other ◽  
Morphological Observation ◽  
Magnetic Domains ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Backscattered Electron ◽  
Increasing Demand

In recent years, there has been increasing demand for higher voltage SEMs, in the field of surface observation, especially that of magnetic domains, dislocations, and electron channeling patterns by backscattered electron microscopy. On the other hand, the resolution of the CTEM has now reached 1 ∼ 2Å, and several reports have recently been made on the observation of atom images, indicating that the ultimate goal of morphological observation has beem nearly achieved.

New type electron gun with electrostatic and electromagnetic lenses

1978 ◽  
Vol 36 (1) ◽  
pp. 62-63
Author(s):  
T. Ichinokawa ◽  
H. Maeda
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Optimum Condition ◽  
Bias Voltage ◽  
Electron Gun ◽  
Charge Effect ◽  
Micro Fabrication ◽  
Maximum Brightness ◽  
New Type ◽  
The Ideal

I. IntroductionThermionic electron gun with the Wehnelt grid is popularly used in the electron microscopy and electron beam micro-fabrication. It is well known that this gun could get the ideal brightness caluculated from the Lengumier and Richardson equations under the optimum condition. However, the design and ajustment to the optimum condition is not so easy. The gun has following properties with respect to the Wehnelt bias; (1) The maximum brightness is got only in the optimum bias. (2) In the larger bias than the optimum, the brightness decreases with increasing the bias voltage on account of the space charge effect. (3) In the smaller bias than the optimum, the brightness decreases with bias voltage on account of spreading of the cross over spot due to the aberrations of the electrostatic immersion lens.In the present experiment, a new type electron gun with the electrostatic and electromagnetic lens is designed, and its properties are examined experimentally.

Comparative strengths and weaknesses of peroxidase and colloidal gold in pre- and post-embedding immunolabeling techniques

1987 ◽  
Vol 45 ◽  
pp. 1002-1005
Author(s):  
D. R. Abrahamson ◽  
P. L. St.John ◽  
E. W. Perry
Keyword(s):  
Electron Microscopy ◽  
Horseradish Peroxidase ◽  
Light Microscopy ◽  
Colloidal Gold ◽  
Light Microscope ◽  
Ultrastructural Localization ◽  
The Other ◽  
Quantitative Studies ◽  
Dense Suspension ◽  
Antigen Localization

Antibodies coupled to tracers for electron microscopy have been instrumental in the ultrastructural localization of antigens within cells and tissues. Among the most popular tracers are horseradish peroxidase (HRP), an enzyme that yields an osmiophilic reaction product, and colloidal gold, an electron dense suspension of particles. Some advantages of IgG-HRP conjugates are that they are readily synthesized, relatively small, and the immunolabeling obtained in a given experiment can be evaluated in the light microscope. In contrast, colloidal gold conjugates are available in different size ranges and multiple labeling as well as quantitative studies can therefore be undertaken through particle counting. On the other hand, gold conjugates are generally larger than those of HRP but usually can not be visualized with light microscopy. Concern has been raised, however, that HRP reaction product, which is exquisitely sensitive when generated properly, may in some cases distribute to sites distant from the original binding of the conjugate and therefore result in spurious antigen localization.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

The Dark Tetrad

2015 ◽  
Vol 36 (4) ◽  
pp. 228-236 ◽  
Author(s):  
Janko Međedović ◽  
Boban Petrović
Keyword(s):  
Personality Traits ◽  
Antisocial Behavior ◽  
Second Order ◽  
The Other ◽  
Negative Pole ◽  
Latent Space ◽  
Order Factor

Abstract. Machiavellianism, narcissism, and psychopathy are personality traits understood to be dispositions toward amoral and antisocial behavior. Recent research has suggested that sadism should also be added to this set of traits. In the present study, we tested a hypothesis proposing that these four traits are expressions of one superordinate construct: The Dark Tetrad. Exploration of the latent space of four “dark” traits suggested that the singular second-order factor which represents the Dark Tetrad can be extracted. Analysis has shown that Dark Tetrad traits can be located in the space of basic personality traits, especially on the negative pole of the Honesty-Humility, Agreeableness, Conscientiousness, and Emotionality dimensions. We conclude that sadism behaves in a similar manner as the other dark traits, but it cannot be reduced to them. The results support the concept of “Dark Tetrad.”

scholarly journals New oscillation criteria for second-order neutral differential equations with distributed deviating arguments

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Osama Moaaz ◽  
Choonkil Park ◽  
Elmetwally M. Elabbasy ◽  
Waed Muhsin
Keyword(s):  
Differential Equations ◽  
Second Order ◽  
The Other ◽  
Riccati Transformation ◽  
Transformation Technique ◽  
Deviating Arguments ◽  
Neutral Differential Equations ◽  
Second Order Differential Equations ◽  
Continuous Delay ◽  
New Criteria

AbstractIn this work, we create new oscillation conditions for solutions of second-order differential equations with continuous delay. The new criteria were created based on Riccati transformation technique and comparison principles. Furthermore, we obtain iterative criteria that can be applied even when the other criteria fail. The results obtained in this paper improve and extend the relevant previous results as illustrated by examples.

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