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M Réthelyi

Publications and source records attributed to M Réthelyi.

At least 19 recordsLinked to original sources
PubMed2002

Position and size of the axon hillock in various groups of neurons.

The origin of the axon was studied in Golgi-Kopsch impregnated specimens prepared from the spinal cord and brain of adult rats. Five types of neurons were sampled: large ventral horn neurons, neurons in the intermediate zone and ventral horn of the spinal cord, antenna-type neurons in the spinal dorsal horn, neurons in the thalamus, and neurons in the hypothalamus. The axon originated from the perikaryon in 76% of the large ventral horn neurons and in 64% of the neurons in the thalamus. In contrast, the axon emerged from one of the dendrites in 75% of the neurons in the intermediate zone and the ventral horn of the spinal cord and in 68% of the neurons in the hypothalamus. In the case of the antenna-type neurons in the spinal dorsal horn, the axon often originated from one of the dendrites, but never from a dorsally oriented dendrite. The mean distance of the axon hillock of dendritic origin was the longest in the neurons in the intermediate zone and the ventral horn of the spinal cord. The size of the axon hillock was proportional to the size of the perikaryon. The impregnated portion of the axon was longest in the large ventral horn neurons.

Animals↗
PubMed1991

Colchicine enhances mRNAs encoding the precursor of calcitonin gene-related peptide in brainstem motoneurons.

Hybridization signals indicating mRNAs encoding the precursor of calcitonin gene-related peptide (CGRP) and CGRP immunoreactivity were detected on parallel sections containing brainstem motor nuclei using in situ hybridization histochemistry and immunohistochemistry. In untreated and saline-injected rats the motoneurons in the hypoglossal, facial motor nuclei and in the ambiguus nucleus showed weak to moderate hybridization signals. In these motoneurons CGRP immunoreactivity was restricted to the Nissl bodies of the perikarya. Twenty-four and 42 hours after intracerebroventricular colchicine injection the intensity of both the hybridization signal and the immunoreaction product increased. The distribution of CGRP immunoreactivity changed from discrete perikaryal localization to diffuse reaction in the perikarya and along the proximal dendritic tree. Motoneurons in the rest of the brainstem motor nuclei (VIth, Vth, IVth and IIIrd) of untreated and saline-injected rats showed neither hybridization signal nor CGRP immunoreactivity. After intracerebroventricular injection of colchicine these motoneurons showed both hybridization signal and CGRP immunoreactivity. In all nuclei the size of motoneurons decreased and their Nissl structure changed to an amorphous basophilic mass following colchicine treatment.

Animals↗
PubMed1990

Synapses upon the axon origin of dorsal horn neurons in the rat spinal cord.

Axon terminals synapsing with axon hillocks or origins of Golgi-impregnated and gold-toned neurons in the dorsal horn of the rat were shown in serial electron micrographs. Synapses occurred irrespective of the site (perikaryon or dendrite) and mode (with or without an axon hillock) of the axon origin. The synapsing axon terminals contained 3 populations of vesicles: pleomorphic and flattened synaptic vesicles and a combination of pleomorphic and dense-core vesicles. The membrane thickening in the axon-axon hillock synapses was of the symmetrical type.

Animals↗
PubMed1990

Termination patterns of calcitonin gene-related peptide-immunoreactive nerve fibers in the dorsal horn of the human spinal cord.

CGRP-immunoreactive varicose nerve fibers displayed three kinds of termination patterns in the cervical, thoracic and lumbar segments of the human spinal cord. Bundles of immunoreactive fibers formed a loose network in lamina I. A homogenous band of immunoreactive fibers filled lamina II. Multiple bundles of CGRP-positive fibers coursed through the superficial laminae towards deep portions of the grey matter. In the lumbar segments, in contrast to the cervical and thoracic segments, the bundles could be followed deep into the dorsal funiculus. Bundles of varicose immunoreactive fibers were seen to twine around the dendrites of neurons located in lamina I, in the dorsal funiculus of the lumbar segments and deep in the dorsal horn (laminae III-V). The corresponding types of large and medium-sized neurons were found in silver impregnated adjacent spinal cord sections. It is suggested that neurons in the above locations preferentially receive multiple contacts from CGRP-containing nerve fibers along their extensive dendritic arborizations (CGRP-target neurons).

Aged↗
PubMed1990

Species-specific expression of cholecystokinin messenger RNA in rodent dorsal root ganglia.

The expression of cholecystokinin (CCK) messenger RNA (mRNA) was examined in dorsal root ganglia of rat and guinea pig using in situ hybridization histochemistry and RNA (Northern) blot hybridization with synthetic oligodeoxyribonucleotide (oligomer) probes. In guinea pig, CCK mRNA was detected in small and medium-sized neuronal perikarya comprising approximately 10-15% of the total dorsal root ganglia cell population. In contrast, in neurons of rat dorsal root ganglia, CCK mRNA was not detectable. Northern blot analyses revealed a single CCK mRNA species of expected size (0.8 kb) in guinea pig, but not rat, dorsal root ganglia. A 0.8 kb CCK mRNA was, however, detected in cortex of both rat and guinea pig. These data suggest that CCK is normally not synthesized in neurons of rat dorsal root ganglia and that there are species differences in CCK gene expression in mammalian sensory ganglia.

Animals↗
PubMed1989

Distribution of neurons expressing calcitonin gene-related peptide mRNAs in the brain stem, spinal cord and dorsal root ganglia of rat and guinea-pig.

In situ hybridization histochemistry was used to localize calcitonin gene-related peptide mRNAs in spinal cord, brain stem and dorsal root ganglion neurons of the rat and guinea-pig. A 32P-labeled 23-base-long (23mer) oligodeoxyribonucleotide (oligomer) complementary to calcitonin gene-related peptide mRNA sequences encoding residues 23-30 of calcitonin gene-related peptide was used primarily as a probe (CGRP I probe). A 32mer complementary to mRNA sequences for residues 10-20 of calcitonin gene-related peptide (CGRP II probe) was also used as a positive control for specificity of the 23mer for calcitonin gene-related peptide mRNA. In both the guinea-pig and rat calcitonin gene-related peptide mRNA was localized specifically to neurons of the dorsal root ganglion, to spinal motoneurons and to motoneurons of the hypoglossal, facial and accessory facial motor nuclei. Differences in the distribution of calcitonin gene-related peptide mRNA between the rat and guinea-pig included a higher proportion of rat dorsal root ganglion neurons containing calcitonin gene-related peptide mRNA and the localization of calcitonin gene-related peptide mRNA to motoneurons of the ambiguus motor nucleus, parabrachial and peripeduncular nucleus of the rat but not the guinea-pig. In the guinea-pig, in contrast, calcitonin gene-related peptide mRNA was localized also to motoneurons of the abducens, trigeminal, trochlear and oculomotor nerves. The neuronal groups in the intact rat found here to contain calcitonin gene-related mRNA have also been shown previously to contain calcitonin gene-related peptide immunoreactivity in colchicine-treated rats. Colchicine-treated rats, however, have been found to contain additional groups of calcitonin gene-related peptide immunoreactive neurons which, in the intact rats used in the present study, showed no detectable hybridization with the calcitonin gene-related peptide probe.

Animals↗
PubMed1989

In situ hybridization of peptide mRNAs on vibratome sections.

In situ hybridization procedures that have been used successfully for the localization of somatostatin and cholecystokinin mRNAs in neurons on cryostat sections of rat brain, were tested for applicability to vibratome sections of rat and guinea pig brain. Somatostatin and cholecystokinin mRNAs were localized to neurons in 30 microns thick vibratome sections of brain from both species by use of 32P labelled oligodeoxyribonucleotide (oligomer) probes. Somatostatin mRNAs was localized to neurons in the periventricular region of the preoptic area of rat, and guinea pig brain. Cholecystokinin mRNAs were localized to neurons of rat hippocampus. Hybridization signal, background and resolution achieved with vibratome sections were comparable to those obtained with the more commonly used cryostate sections.

Animals↗
PubMed1988

In situ hybridization using 32P labelled oligodeoxyribonucleotides for the cellular localisation of mRNA in neuronal and endocrine tissue. An analysis of procedural variables.

Methodological variables for in situ hybridization using 32P labelled oligodeoxyribonucleotides (oligomers) have been examined. Four different oligomers directed against proglucagon messenger RNA (mRNA) and two different oligomers against prosomatostatin mRNA have been used. Specific hybridization was obtained in adult rat brain, stomach and pancreas and in neonatal rat ileum. Tissue was perfusion fixed with 4% paraformaldehyde 0.2% glutaraldehyde and hybridization was carried out in 50% formamide for 72 h at 42 degrees C. Using hybridization conditions of lower stringency (33% formamide) labelling was also obtained in guinea pig tissue. Other variables which affected hybridization signal intensity were the inclusion of a prehybridization dehydration stage, the probe concentration, the inclusion of ammonium acetate in the posthybridization dehydrating ethanols and in the autoradiographic emulsion, and the exposure time. The localisation of proglucagon mRNA in rat pancreas using a 20mer was used as a model tissue for testing these methodological variables and the results were found generally also to apply to the other probes and tissues tested. The methods described provide single cell resolution and show that 32P labelled oligomers may be used to localise neuropeptide and endocrine mRNAs in different types of tissue and in different mammalian species.

Animals↗
PubMed1986

Quantitative analysis of dendritic protrusions in the medial preoptic area during postnatal development.

Dendritic architecture and distribution of dendritic protrusions were studied on Golgi-impregnated neurons in the medial preoptic area (MPOA) of infant rats (7 and 20 days old), of animals at puberty (34 days old) and of postpubertal rats (90 days old) using computerized image analysis. The protrusions showed a peak distribution on the proximal portion of the dendritic tree in infant rats. At puberty and in postpubertal animals protrusions disappeared almost completely along the most proximal portion of the dendritic tree. The data suggest that differentiation of certain MPOA neurons is still in progress at puberty.

Age Factors↗
PubMed1986

Altered distribution of dorsal root fibers in the rat following neonatal capsaicin treatment.

Distribution of primary afferent fibers was studied in intact and neonatally capsaicin treated rats by the application of horseradish peroxidase to the central branch of the transected lumbar dorsal roots. Coarse primary afferent fibers entered the spinal cord through the larger medial portion of the rootlet and arborized in the deeper part of the dorsal horn (laminae III and IV). Fine fibers reached the spinal cord through the smaller lateral portion of the rootlet and arborized in the superficial portion of the dorsal horn (lamina I and outer portion of lamina II). The technique used was inadequate to stain fine, unmyelinated primary afferent fibers terminating in the larger inner portion of lamina II. After neonatal capsaicin treatment (50 mg/kg) the flame-shaped arborizations of thick primary afferent fibers terminating in intact rat in laminae III and IV spread dorsally and occupied the inner portion of lamina II in the larger lateral sector of the dorsal horn. Medially the dense arborization of a different type of thick primary afferent fibers sprouted up to the white-gray border. The border between the lateral and medial sector was sharp and only slightly varied in localization from experiment to experiment. The sprouting fibers established complicated synaptic contacts with dendrites and axon terminals. The rearrangement of primary afferent fibers after neonatal capsaicin treatment confirmed earlier results and revealed a mediolateral difference in the fiber organization of the dorsal horn indicating differences in the projection from hairy vs non-hairy skin areas.

Animals↗
PubMed1986

Axonal regeneration following retrochiasmatic deafferentation in young and adult rats.

Regeneration of nerve fibres after hypothalamic knife cuts was studied by the anterograde transport of horseradish peroxidase [HRP] in female rats of various ages. Retrochiasmatic frontal cuts were made in 2, 5, 7 and 11-day-old and in adult rats. Four, 6, 7 and 12 months later HRP was injected rostral to the cut-line in the suprachiasmatic area. HRP-stained nerve fibres ran rostro-caudally from the injection site through the cut-line in animals operated upon at 2, 5 and 7 days of age. In contrast to the former group, animals operated on the 11th day of life as well as in adult rats no HRP-stained nerve fibres could be seen passing through the cut-line which was marked by scar formation. In one animal operated in adulthood a bundle of nerve fibres noticed 7 months after the surgery turned medially at the caudal end of the cut-line and spread over the frontally deafferented area. The character of these newly formed fibres was different: part of them showed a varicose appearance, the others exhibited even contours. The present findings indicate that the deafferented [or isolated] hypothalamus remains neuronally isolated from the environment if the operation is carried out later than the end of the first week of life. Operations made during the first postnatal week do not leave permanent traits in the brain.

Afferent Pathways↗
PubMed1985

Dendritic arborization and axon trajectory of neurons in the hypothalamic arcuate nucleus of the rat--updated.

Neurons in the hypothalamic arcuate nucleus (arcuate neurons) were traced on Golgi-impregnated sections. Dendrites of arcuate neurons showed characteristic orientation patterns. Dendrites along the lateral side follow the convex border of the nucleus by running parallel to the tanycyte processes. Neurons located in the ventrolateral portion of the nucleus have dendrites running parallel to the basal surface of the hypothalamus. Fine, beaded axons of arcuate neurons project mostly ventrally, and less frequently dorsally and dorsolaterally. Ventrally projecting axons converge towards the tuberoinfundibular sulcus which emerges into the ventral portion of the arcuate nucleus from below.

Animals↗
PubMed1985

Lamellar arrangement of neuronal somata in the dorsal root ganglion of the cat.

The retrograde transport of horseradish peroxidase (HRP) was used to study the distribution of perikarya in the dorsal root ganglia (DRGs). Injections of HRP subcutaneously into a small area of the foreleg, flank, perineum, the central pad of the forepaw, muscles of the foreleg, the wall of the urinary bladder, and mucosa of the rectum resulted in many retrogradely labeled perikarya in one DRG. Labeled perikarya were distributed in the ganglia proximally to distal elongated slabs or columns, especially in cases of subcutaneous injections. A similar slab, or columnar distribution, of HRP-labeled perikarya was noticed when the tracer was injected into the spinal cord preceded by the transection of all dorsal root filaments but one. Perikarya located along the lateral border of the ganglion were labeled through rostral filaments, and perikarya distributed along the medial border were labeled through caudal filaments. A segmental somatotopic map has been conceived for the DRG as an intermediate territory between the periphery and the spinal cord.

Animals↗
PubMed1984

Diffusional barrier around the hypothalamic arcuate nucleus in the rat.

The contour lines of horseradish peroxidase injection sites in the ventrobasal hypothalamus were distorted by the border between arcuate and ventromedial nuclei as well as between arcuate nucleus and median eminence. The dense array of tanycyte processes is assumed to isolate the arcuate nucleus from the neighboring territories by establishing a diffusional barrier surface.

Animals↗
PubMed1983

Is the knife-cut in the hypothalamus a permanent barrier to regrowth of nerve fibers? -an affirmative answer.

The regenerative capacity of nerve fibers was studied in adult female rats. Horseradish peroxidase was injected into the anterior hypothalamus lateral to the suprachiasmatic nucleus 4 days, 6 weeks and 4 months, respectively, following an archiform retrochiasmatic knife-cut. The trajectory of the stained fibers was examined on horizontal sections of the hypothalamus. No nerve fibers could be seen sprouting across the scar-tissue of the knife-cut regardless of the survival time. In one rat (6-week survival time) a bundle of fine nerve fibers turned in a medial direction at the caudal end of the knife-cut, suggesting that sprouting fibers were destined to reinnervate parts of the deafferented medial-basal hypothalamus.

Animals↗
PubMed1983

Preferential immunohistochemical localization of vasoactive intestinal polypeptide (VIP) in the sacral spinal cord of the cat: light and electron microscopic observations.

In the present study we have employed immunoperoxidase techniques to investigate the distribution of vasoactive intestinal polypeptide (VIP)-like immunoreactivity in the spinal cord and sensory ganglia of the cat. The spinal distribution of VIP-containing neuronal processes was also compared with that of substance P (SP), somatostatin (SOM), and cholecystokinin-8 (CCK) at lumbar, sacral, and coccygeal levels. At sacral levels, VIP was found to be contained in small and medium-sized primary sensory neurons and in dorsal rootlets. Deafferentation, by either ganglionectomy or dorsal rhizotomy, resulted in a nearly complete loss of VIP immunoreactivity in the spinal cord. The spinal distribution of VIP fibers and terminals was most dense and extensive in sacral segments. Forming a thin shell around the dorsal horn, collaterals, apparently originating from Lissauer's tract, projected either medially or laterally through lamina I. Laterally, many VIP axons terminated in lateral laminae V to VII. Others projected further through the neck of the dorsal horn to medial lamina V and the gray matter near the central canal. Medially, VIP axons descended through lamina I to expand into terminal fields in the posterior commissure and medial lamina V. At the ultrastructural level, VIP-like immunoreactivity was found in dense core vesicles within axonal enlargements containing both large dense core and smaller clear round vesicles. Synaptic connections were infrequently observed but, when encountered, were of the simple axodendritic type. The spinal distribution of VIP-containing fibers was remarkably similar to that reported for pelvic nerve visceral afferents, both in termination patterns within the spinal gray matter and in localization to the sacral cord. The density of SP-, SOM-, and CCK-containing fibers and terminals was constant at all levels examined (L4 to Co4). In marked contrast, the distribution of VIP fibers, much like that of pelvic nerve afferents, was mostly confined to sacral segments. Thus, although SP, SOM, and CCK may be contained within a population of sacral visceral afferents, they must be common to afferent systems in other segments as well. VIP, however, appears to be preferentially contained within pelvic visceral afferent fibers confined mostly to sacral segments.

Animals↗
PubMed1982

Synaptic complexes formed by functionally defined primary afferent units with fine myelinated fibers.

The individual fine myelinated fibers of cutaneous mechanical nociceptors and "D-hair" receptors were identified by electrophysiological recording with micropipette electrodes in cats and monkeys. Their intraspinal terminations were labeled by iontophoresing horseradish peroxidase intracellularly and subsequent diaminobenzidine histochemistry. These terminations were examined with light and electron microscopy to determine the nature and organization of their synaptic contacts. Myelinated fibers of the mechanical nociceptors became unmyelinated before exhibiting many enlargements that made multiple synaptic contacts in the marginal zone (lamina I) and lamina V. Pre- or postsynaptic contacts were found only on enlargements. In the marginal zone of the cat, enlargements made simple axodendritic contacts or were scalloped, central terminals in glomeruli. In glomeruli, myelinated mechanical nociceptor enlargements were presynaptic to several dendritic appendages and postsynaptic to two different types of profiles. One type was interpreted as a presynaptic axon terminal, the other as a presynaptic, vesicle-containing, dendritic appendage. In lamina V of the cat the nociceptor synaptic complexes were similar, but simpler, and only axonal profiles were found to be presynaptic to them. In the monkey marginal zone and deep nucleus proprius, myelinated nociceptor terminations formed the central element of glomeruli, which consisted of postsynaptic dendritic appendages and presynaptic axon terminals. D-hair axons terminated in large numbers of enlargements in the nucleus proprius (laminae III and IV) and inner substantia gelatinosa (lamina IIi). Their large rounded enlargements formed the central terminals in glomeruli and were presynaptic to both ordinary and vesicle-containing dendritic appendages; the presynaptic dendritic profiles also often contacted each other. Profiles interpreted as axonal in origin were the only terminals presynaptic to the primary ending within the D-hair glomeruli. The results suggest that transfer of primary afferent information occurs only at enlargements of the primary fiber and that each primary fiber enters into more than one kind of synaptic arrangement. They also point out that synaptic glomeruli are common to functionally different types of primary afferent fibers and that the internal organization of glomeruli varies with the kind of primary fiber and the locus of the complex.

Afferent Pathways↗