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A Hedlich

Publications and source records attributed to A Hedlich.

At least 19 recordsLinked to original sources
PubMed1995

Postnatal development of NADPH-diaphorase/nitric oxide synthase positive nerve cells in the visual cortex of the rat.

The postnatal development of NADPH-diaphorase (NADPH-d)/nitric oxide synthase (NOS) positive nerve cells was studied in the visual cortex of rats on postnatal day 1, 5, 10, 15, 20, 30 and at the age of 1 year. NADPH-d was demonstrated enzymhistochemically and NOS immunohistochemically using a polyclonal antibody. NADPH-d is localized in nerve cell somata, dendrites, axons and blood vessels, whereas NOS immunoreactivity is only detectable in nerve cells. The identity of NADPH-d cells with those which contain NOS was proved in double labelling experiments in the cortex of rats on postnatal day 5, 15 and at the age of 1 year. The results of these experiments have shown that in the cortex of rats NADPH-d positive cells are identical with NOS-positive cells in the different stages. Therefore we have used NADPH-d histochemistry in all other postnatal stages as a marker for neurons which contain NOS. NOS positive nerve cells appear very early on postnatal day 1 in the intermediate (white matter) and subplate (layers V and VI) region as small undifferentiated neurons. During the following postnatal differentiation these neurons reached their typical morphology in the second week and appeared in all layers. Neurons in layers V and VI preceded those in the superficial layers. Nerve cells in the white matter seem to have their own differentiation pattern because they showed characteristic features of immaturated varicose dendrites for a longer time. The investigation of soma size with the computerized "Kontron Videoplan" system (Zeiss, Germany) showed the largest cell bodies on postnatal day 20 which then decreased towards adulthood. Between postnatal day 10 and 20 some NOS-positive neurons especially in the deep layers displayed symptoms of degeneration, like shrunken cell bodies, corkscrew and twisted dendrites. Furthermore, NOS-positive neurons in layer I are not detectable in adult neocortex. These observations could suggest that some NOS-positive cells in the cerebral cortex of rats may occur only transiently. Also in the neuropil some alterations in the localization of NOS positive axonal boutons were observed. On postnatal day 10 NOS negative cell somata were shadowy surrounded by boutons. During the further development from postnatal day 20 until adulthood this particular position was no longer visible. Beside the NOS cells which played a transient role, the majority of these cells survived to adulthood and are a morphological (Martinotti-cells with ascending axons) and chemical (GABAergic, NADPH-d/NOS positive, peptide containing cells) defined cell type in the neuronal network of the cortex of the rat.

Aging↗
PubMed1994

Morphological analyses of NADPH-diaphorase/nitric oxide synthase positive structures in human visual cortex.

Human visual cortex was studied using NADPH-diaphorase histochemistry and nitric oxide synthase immunohistochemistry. Large, strongly stained, sparsely spined non-pyramidal cells (average soma diameter: 16 x 16 microns) occur in layers II-VI, but are commonest in layers II-III. Small weakly stained multipolar cells (average soma diameter 3.6 x 4 microns, stellate like cells) in layers II-VI are concentrated in layer IV of areas 17 and 18. The density of these cells, measured with a computer assisted microscopy system is less in area 18 than 17. Large, strongly stained, predominantly horizontal cells (average soma diameter 12 x 19 microns) are localized in the underlying white matter. Axons of the large, strongly NADPH-diaphorase positive cells are thin and unbranched with fine boutons. These axons ascend to layer I. The large, strongly stained cells in layers II-VI we identify as Martinotti neurons. In layer I parallel unbranched positive fibres with some fine boutons run horizontally and build dense axonal plexuses together with the axons of Martinotti neurons. Axons of presumed extrinsic origin are morphologically different from NADPH-diaphorase positive intrinsic fibres. They show thick varicosities running in different directions and forming a network in layers III-VI. Basket like formations of these fibres were frequently observed in layers IV, V and VI. Other fibres seem to innervate blood vessels. Nitric oxide synthase was also demonstrated immunohistochemically by a polyclonal rabbit nitric oxide synthase antiserum. The morphology and distribution of the immunostained cells correspond with those seen with NADPH-diaphorase histochemistry. Double labelling experiments confirm the colocalization of NADPH-diaphorase and nitric oxide synthase in all demonstrated cells. Immunohistochemical demonstration of glial fibrillary acidic protein has shown that astrocytes are not involved in the NADPH-diaphorase/NOS system in the human visual cortex.

Aged↗
PubMed1990

[Gabaergic NADPH-diaphorase-positive Martinotti cells in the visual cortex in rats].

NADPH-diaphorase positive cells were described in the visual cortex of the rat in layers II-VI and in the white matter. Their somata were large or medium-sized, oval or elongated, and their cytoplasm was accumulated at the poles. Some proximal thickened coarse dendrites formed a bitufted dendritic field. These features showed a cell type impregnated with the Golgi-Kopsch-method and a Golgi-deimpregnation-method described as Martinotti cell (sparsely spined polarized neurons with ascending axons). The immunocytochemical evidence of GABA in NADPH-diaphorase positive neurons (double labeling) showed the GABA ergic nature of these cells, but an attempt for a double labelling of NADPH-diaphorase and Parvalbumin was negative.

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PubMed1990

[Characteristics of neurons with intracortical axons spreading to the visual cortex of Alticola stoliczkanus barakshin and Alticola argentatus semicanus. A Golgi investigation].

In the visual cortex of Alticola stoliczkanus barakshin and Alticola argentatus semicanus neurons with intracortical axons were studied with the Golgi-Kopsch-method. With special consideration to the axon morphology we could describe the following neuronal types: large spinefree cells with probably myelinated axons (basket cells), small and medium sized spinefree cells with axons inside the dendritic fields (small basket cells), spinefree cells with axonal arcades, cells with axonal grape like terminal knobs, cells with columnar axons (double bouquet cells), sparsely spined cells with ascending axons (Martinotti cells), bipolar cells, neuroglioform cells and chandelier cells.

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PubMed1990

[Dendrite-free GABAergic neurons of the visual system in the rat].

Spinefreie GABAergic neurons in the visual cortex of the rat were studied with the Golgi-Kopsch-method and immunohistochemical methods against GABA. They show differences of their axonal arborizations, axonal surfaces and of their axonal terminal formations. We found large spinefree neurons, spinefree neurons with strictly axonal fields, spinefree neurons with dense axonal fields, spinefree neurons with axons forming arcades, spinefree neurons with columnar axons and spinefree neurons with clewded axonal terminals.

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PubMed1988

[Morphologic characteristics of neuroglioform cells in the visual cortex of various mammals (rat, guinea pig, alticola and cat). A Golgi study].

Neuroglioform cells have been studied and compared in visual cortex of rat, guinea pig, alticola and cat in Golgi-material. These neurons possess a distinct morphological pattern, a dense and strictly local dendritic field with many short, fine and radiated dendrites which highly branch near the soma and a very dense axonal plexus of thin, varicose and sinuous branches. Neuroglioform cells were identified in all species and in all laminae of visual cortex. Some features, the size of the soma and the size of the axonal arborization vary among the species. We found small, medium sized and large somata. In general, the axons are confined to the vicinity of the dendritic field, but they can extend to considerable distances beyond it. The form of the soma and the dendritic surface were found to be typical for special species, so the form of the soma in guinea pig neuroglioform cells can be of different size, especially unregularly. In rodents the dendrites bear spines, but the dendrites of the cat are smooth.

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PubMed1988

[Neuroglia-form cells in the visual cortex of the rat].

Neuroglia-form cells have been examined in visual cortex of the rat in Golgi-Kopsch-preparations. These small neurons with strictly local and dense dendritic and axonal plexuses are present in all cortical layers. Neuroglia-form cells of the rat are identical with the same neuronal types described by previous authors in cortical areas of other species, guinea pig, cat, monkey and in man.

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PubMed1986

[Classification of neurons in the visual cortex of the guinea pig (Cavia porcellus). A combined Golgi-Nissl study using deimpregnation technics].

The aim of the investigation is the identification of neuronal types in the visual cortex of the guinea pig (Cavia porcellus) in Nissl preparations. In two rapid Golgi series (modified by Fairén et al. 1977) and nine Golgi-Kopsch series eleven neuronal types could be classified: 1. Neurons with long axonal main stems: Pyramidal cells (layers II-VI), pyramid-like cells (layers I, VI), spiny stellate cells (layer IV). 2. Neurons with locally distributed axons: large and small aspiny cells (layers II-VI), neuroglioform cells (layers I-VI), large sparsely spiny cells with ascending axons (Martinotti cells) (layers III-VI), small sparsely spiny cells with variable axons (layer IV), bipolar cells (layers II-VI), chandelier cells (layers II, III), double bouquet cells (layers II, III), and 3. a horizontal cell in layer I without an impregnated axon. To identify Nissl stained somata, Golgi impregnated neurons were deimpregnated. Now cytoplasmic and nuclear features can be compared. In order to get a survey about the variability of the somal features, we have deimpregnated 245 neurons on the whole using either gold chloride (Fairén et al. 1977) combined with the rapid Golgi method, modified by Fairén et al. (1977), or a diluted solution of ammonia (Braak and Braak 1982) combined with the Golgi-Kopsch method, nonembedded, in glycerol stored material and in celloidin embedded sections, resp. After deimpregnation several neuronal classes could be distinguished considering at first the width of the cytoplasm and the localization of the nucleus. There are Nissl stained somata with corresponding features: 1. Pyramidal cells, pyramid-like cells, and spiny stellate cells of the layer IV with relatively broad cytoplasm and bright, centrally localized nuclei. 2. Large aspiny cells which vary in somal sizes and shapes with very broad cytoplasm and bright, centrally or excentrally localized nuclei. 3. Small aspiny cells, some of the neuroglioform cells, and small sparsely spiny cells of layer IV have more or less broad cytoplasm but in the most cases excentrally localized nuclei. 4. The remaining neuroglioform cells, bipolar cells, and the horizontal cell of layer I are particularly poor in cytoplasm. The somata of these neuronal types are small, those of the bipolar cells are vertically orientated. 5. Like the bipolar cells large sparsely spiny cells with ascending axons Martinotti cells), chandelier cells, and double bouquet cells are also polarized neurons, but larger and not always vertically oriented.(ABSTRACT TRUNCATED AT 400 WORDS)

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PubMed1986

[Classification of neurons of the visual cortex of the guinea pig (Cavia porcellus). A Golgi study].

In the visual cortex of the guinea pig stellate neurons in L IV and neurons with short axons were studied with the Golgi-method. We found spiny multipolar neurons in L IV (stellate cells in L IV), large spinefree neurons (basket cells), spinefree neurons with vertical or horizontal axonal distribution, small neurons with dense local dendritic and axonal plexuses (neurogliaform cells), sparsely spined polarized neurons with ascending axons (Martinotti-cells), small sparsely spined cells in L IV, spinefree bipolar neurons with vertical axons (bipolar cells), neurons with chandelier axons (chandelier cells) and sparsely spined bitufted neurons with dense vertical axonal plexuses (double bouquet cells). The analysis of neurons in the visual cortex of the guinea pig was undertaken to establish their number and distribution. Comparing the neurons of two species of rodentia, the diurnal guinea pig and the night-active rat we could found a higher variability of neurons in the guinea pig and a higher diversity of neuronal structures, which allows a better differentiation of cell types (e.g. double bouquet cells).

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PubMed1985

[Types of neurons in the visual cortex of the rat, identified in Nissl- and deimpregnated Golgi preparations].

Neuronal types of the rat's visual cortex were identified in Nissl stained and deimpregnated Golgi sections (rapid Golgi method modified by Fairén et al. 1977, Golgi-Bubenaite, Golgi-Kopsch and modified by Braitenberg; deimpregnation after FAIREN et al. 1977 and Braak and Braak 1982, respectively). Cytoplasm and nucleus become visible in deimpregnated neurons and can then be counter-stained with methylene blue or toluidin blue. Somal and nuclear features of Nissl stained and deimpregnated neurons were compared. Provided that these features as well as the specific localization, the relative size and the shape of the soma agree the neurons are identical. We could find that the following neuronal types are identical in Golgi and Nissl stained sections: pyramidal cells of layers II-VI, pyramid-like neurons of layers VI and VII (VIa, b, c) (type C, Werner et al. 1982), multiangular neurons of layer I (type A, Werner et al. 1982), spiny stellate cells of layer IV, sparsely spined neurons with ascending axons (Martinotti cells) (type H, Werner et al. 1982), large and medium-sized spine-free, multipolar neurons (basket cells) (type B, Werner et al. 1982). Bipolar neurons and chandelier cells are identical with neurons poor in cytoplasm (types E, F, G, Werner et al. 1982). Until today two neuronal types could not be identified: type D of L I (Werner et al. 1982) and small, sparsely-spined neurons of layer IV with variable axons (Hedlich and Winkelmann 1982; Hedlich et al. 1984). Characteristics of somata, dendrites and axons of neurons identified in this paper are summarized in table 1. In most cases, these findings confirm earlier suppositions concerning the identity of neuronal types of the rat's visual cortex in Golgi and Nissl stained sections (Werner et al. 1979) and verify the values of their frequency and distribution pattern (Werner et al. 1982).

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PubMed1984

[Sparsely-spined neurons in the rat visual cortex].

Sparsely spined neurons were described in the visual cortex of the rat. A large cell type was found in all laminae, but mainly in L III-L V. The soma is large and the dendrites are vertically oriented. In most cases, the axon originates from the upper main dendrite or the upper soma pole. The axonal arborization is vertical. In the terminal axonal segments the number of boutons is high. A small neuron type could be demonstrated in L IV. The soma is small, and the dendritic field is nearly multipolarly or horizontally oriented. The axon derives from the basal pole or laterally at the soma.

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PubMed1983

Termination of geniculocortical afferents on bipolar neurons in area 17 of the albino rat: a Golgi/EM study.

Degenerating terminals of specific afferents to the primary visual cortex of the albino rat were identified by electron microscopy after electrolytic lesions of the lateral geniculate nucleus. Bipolar neurons were marked by Golgi impregnation. We observed smooth dendrites of two bipolar cells postsynaptic to degenerating geniculate terminals. We conclude that this cortical cell type is directly contacted by thalamic afferents.

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PubMed1983

[Degenerative changes in the occipital neocortex in chronically amphetamine treated rats].

Neurons of the Wistar-rats' occipital cortex were morphologically investigated after chronical application of amphetamine. The nerve cells impregnated according to the Golgi-Kopsch technique showed in part changes on both the dendrites and in the axonal region. Besides a partial reduction of spines and of peripheral dendritic arborizations round varicosities of different density could be observed on the dendrites and on the axon, either, which were discussed to be due to a neurotoxic effect of amphetamine.

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PubMed1983

Geniculocortical synapses involving apical dendrites of layer V pyramidal cells in area 17 of the albino rat visual cortex: a combined Golgi/EM study.

Using the combined Golgi/EM technique (Fairén et al. 1977) we have investigated whether apical dendrites of layer V pyramidal cells with different diameters receive different numbers of geniculocortical synapses. An electrolytic lesion was made in the lateral geniculate nucleus (LGN) of albino rats. After a survival time of two days degenerating boutons of LGN afferents onto visual cortex (area 17) were identified by electron microscopy. Postsynaptic layer V pyramidal cells marked by Golgi impregnation were studied. The location of nine identified pyramids was determined by light microscopy. The diameter of the apical dendrites - ranging from 0.9 to 2.5 mum - was measured on electron micrographs. The dendrites of eight out of the nine pyramids make synaptic contacts with geniculocortical afferents in layer IV and lower layer III. The degenerative geniculocortical terminals were mostly of the electron dense type; one times the electron lucent type was observed. These axon terminals synapse mainly with asymmetrical synaptic junctions on spines. Occasionally synaptic contacts were found on dendritic shafts. Most degenerating synapses are localized on the pyramidal cell with the thinnest apical dendrite. There was also an other thin apical dendrite, which did not receive any degenerating bouton. All out of one apical dendrites of different size are involved in geniculocortical synapses without giving any preference to dendrites of a defined diameter.

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PubMed1982

The glia types inthe visual system of adult rats, their shape variability, distribution patterns, and their lightoptically visible contacts to other tissue structures.

In silver impregnated coronal sections of adult rat brains the glia types of the Corpus geniculatum laterale, pars dorsalis (CGLd) an in area 17 were registered considering their form variants (FV), their intraareal distribution and their light optically demonstrable connexions to other tissue structures. Compared with the shape-determining light optically visible processes and perikarya, astrocytes show the lowest, microglial cells the greatest from variability. Transitional forms between the three glia types were not detected, but between elongated astrocytes and fiber astrocytes. An accumulation of elongated astrocytes, fiber astrocytes, and oligodendrocytes was found in the lateral zone of the CGLd, of protoplasmic astrocytes in the lateral and intermediary zones and at the rostral and caudal poles of the griseum, too. In the cortex distribution differences in the single laminae became also evident. Astrocytes were most concentrated in L I, oligodendrocytes and microglia, however, in L V. A few FV of the microglia were found to show a predominant localisation in specific laminae. Neither the total glia number nor the single glia types correlate with the neuron packing density. The frequency distribution of the FV of oligodendroglia in the CGLd and the visual cortex is similar, that of microglia, however, significantly deviating. Compared with the CGLd the oligodendrocytes of area 17 have smaller somata. Astrocytes, oligodendrocytes and microglial cells reveal structural contacts to different parts of the neurons, to blood vessels and other glial cells, too. Contacts between oligodendrocytes and microglial cells as well as astrocytes in satellite position could never be observed. In the cortex a few FV of microglia show typical connexions.

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PubMed1982

[Types of neurons in the visual cortex of the adult and young rat].

The neurons of the visual cortex of adult und juvenile rats (Wistar) were studied with Golgi Rapid and Golgi Kopsch methods at the age of one to twenty days, 4 months and 18 months. The nerve cells were classified according to the form and size of their soma, the branching and surface of their dendrites and their axonal ramification. The neuron types show great similarities with those described in other species. We distinguish pyramidal neurons in L II-L VI, pyramid-like neurons--e.g. horizontally orientated neurons--neurons with a thick basal dendrite and multiangular neurons in L I as well as the spiny multipolar neurons in L IV all showing spiny dendrites and long axons. Neurons with spiny or sparsely spined dendrites and short axons are spine-free multipolar neurons with horizontal axons, sparsely spined polarized neurons with vertical axons, spine-free bipolar neurons with vertical axons and chandelier neurons. In general, all described cell types are nearly undifferentiated in the first postnatal week. The axons are in a more advanced stage than soma and dendrites at this time. During the process of differentiation the soma looses its irregular shape and the somaspines disappear. The immature dendrites show varicosities, which disappear during dendritic lengthening. The dendritic surface becomes either smooth or spiny. The axonal growth is connected with a loss of varicosities and finally with the formation of terminal boutons. At the time of eye-opening all described cell types have reached their differentiated state, but spine density and distal dendritic length have not yet achieved adult values.

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PubMed1979

[Identification of nerve cells in the visual cortex of the rat using Nissl and Golgi-Kopsch methods].

The neurons of the visual cortex of the albino rat were studied using both the Nissl- and Golgi-Kopsch methods. In Nissl preparations we can distinguish between a group of neurons rich in cytoplasm, a group of neurons poor in cytoplasm and an intermediate group. In the Golgi preparations the neurons can be subdivided according to the shape of their cell bodies, dendrites and axons. Spiny cells with long axonal main trunks are pyramidal cells, multiangular cells and stellate cells of layer IV. Cells with spineless dendrites and short axonal arborization are basket cells, neuroglioform cells and small double bouquet cells. Due to its spines and the short axonal arborization, the coarse fusiform cell (Martinotti cell) is an intermediate type. We assume cells having long axons and dendritic spines are category I neurons and cells having short axons and no or a few spines are category II neurons (according to SZENTAGOTHAI 1973). On the basis of homological criterions and taxonomically relevant features references for identifying the cell group rich in cytoplasm and category I neurons, on the one hand, and the cell group poor in cytoplasm and category II neurons, on the other hand, were found. The group of cells rich in cytoplasm is related to pyramidal cells, multiangular cells and stellate cells of lamina IV. The group of cells poor in cytoplasm is discussed as corresponding to cells of lamina I, round or oval forms as basket cells and neuroglioform cells, fusiform cells as double bouquet cells. The intermediate cell form in the Nissl preparations is according to the Martinotti cell in Golgi material. These findings allow quantitative studies about particular cell populations and can, completed with electron microscopical date, instruct computer models to simulate the complicate neuronal network of the visual cortex.

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