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PubMed1980

Neurofilaments in the chick embryo during early development. I. Immunofluorescent study with antisera to neurofilament protein.

The time of appearance of neurofilament protein was determined by indirect immunofluorescence in the chick. Immunofluorescence first appeared in 3-day embryos as a peripheral layer on the ventral and lateral surfaces of the spinal cord and hindbrain. Concomitant with a marked thickening of this layer on the ventrolateral surface of the neural tube, neurofibrils were seen emerging from the cord and the myelencephalon. The immunofluorescent layer could be followed rostrally on the surface of the brain up to the mesencephalic flexure. In this location a large bundle of fibrils was observed emerging from the ventral surface of the mesencephalon. The posterior root ganglia and inner layer of the retina were intensely immunofluorescent on day 4. In the following days of development the spinal cord and ganglia assumed a mature configuration. The appearance of the anterior horns on the 6th day was remarkably segmental, the anterior horns being detected in alternate sections in a series of transverse serial section.

Animals↗
PubMed1975

Prurigo nodularis. Histological and electron microscopical study.

We describe a typical case of prurigo nodularis, of 15 years' duration, in a middle-aged woman. Histological and electron microscopical examination of the skin lesions revealed distinct changes in the nerve tissue. There were groups of thickened nerve fibers that formed nodules with numerous Schwann cells. Some of the nerve bundles extended to the dermoepidermal junction. Electron microscopy showed very obvious lesions in the Schwann cells and axons. In the Schwann cells there was a lucent cytoplasm with few mitochondria, an absence of endoplasmic reticulum and a few irregular, membrane-bound vacuoles. While the mesaxons all appeared normal, the axons varied greatly in diameter; the small ones appeared normal and contained neurofibrils and neurotubules, whereas the large onew were empty. Every Schwann cell encircled a large number of axons. It may be assumed that the axon swelling is a nonspecific reaction to injury.

Adult↗
PubMed1981

Traumatic neuromas of the facial nerve.

The temporal bones in two patients contained asymptomatic neuromas of the facial nerve and a third patient had an identical tumor of the chorda tympani. All three neuromas occurred in the presence of chronic inflammatory middle ear disease. Histologically all three resembled traumatic (repairative) neuromas. Both of the facial nerve lesions occurred at a site of frequent fallopian canal dehiscence. It is suggested that occasionally, long-term exposure to the facial nerve to chronic inflammation results in proliferation of neurofibrils leading to neuroma formation.

Adolescent↗
PubMed1980

Identification of early neurons in the brainstem and spinal cord: I. An autoradiographic study in the chick.

Early stages in chick neurogenesis were investigated with tritiated thymidine (3H-Tdr) autoradioraphy to determine the location and identity of the first neurons produced for the central nervous system. These cells have been shown to arise prior to neural tube closure (Sechrist, '75). Chicks were treated at selected intervals between 20 and 72 hours of incubation with 3H-Tdr in a modified pulse-labeling technique, and terminated on the 18th day of embryonic development (E18), when neuronal types could be determined. Some of the earliest neurons start their final DNA synthesis before 20 hours of incubation (head process, Hamburger-Hamilton stage 5). These are primarily medium-sized cells of the reticular formation in the medulla and at the diencephalic-mesencephalic junction, but also in the intermediate zone of the spinal cord. Motor neurons of the brainstem and spinal cord begin to appear next, after 26-28 hours incubation; the first sensory neurons arise after 32 hours. Other workers (Ramon y Cajal, '60; Tello, '23; Windle and Austin, '36) found that neurons of the reticular formation were the first to differentiate neurofibrils, during the latter part of E2, indicating that fibrillogenesis in these cells begin about 24 hours after the initial cessation of DNA replication.

Animals↗
PubMed1985

The development of acetylcholinesterase activity in normal and transplanted superior colliculus in rats.

Histochemical techniques have been used to examine the development of the enzyme acetylcholinesterase (AChE) in normal and transplanted rat superior colliculus (SC). At birth (P0), relatively little AChE activity was found in SC in situ; however, there was a gradual increase in the intensity of AChE staining in the SC over the first 4 postnatal weeks. In the superficial layers, an increase in AChE activity was first seen in rostromedial SC at P6 and was found throughout the upper tectal layers by P10. An increase in AChE activity in the intermediate layers was apparent by P12 and the adult pattern, characterized by periodic bands of AChE staining, was established by P22. In tectal grafts, the development of AChE activity followed a time course similar to that found in normal SC. Mature tectal grafts contained moderate AChE activity with AChE-positive cells scattered throughout the neuropil. There were however, localized, often spherically shaped areas which displayed relatively intense AChE activity. These AChE-dense areas had a characteristic appearance in adjacent sections stained for Nissl or neurofibrils. Significantly, host retinal input, where present, was always restricted to the AChE-dense regions and it seems certain that these areas are homologous to the superficial layers of normal SC. AChE-rich regions were also present, however, in grafts which received no retinal input and in general the pattern of AChE activity in tectal grafts was strikingly similar, irrespective of their location or connections with the host brain. It would appear, therefore, that much of the AChE activity in tectal transplants, and presumably in SC in situ, is intrinsic to that region and not derived from or dependent upon extrinsic innervation.

Acetylcholinesterase↗
PubMed1987

Fetal tectal or cortical tissue transplanted into brachial lesion cavities in rats: influence on the regrowth of host retinal axons.

Fetal neural tissue was transplanted into suction lesions of the left brachium and pretectal region in young rats. Tectal tissue was grafted into 6-18-day-old rats and cortical tissue was transplanted into 17-20-day-old animals. The aim was to determine whether grafts could potentiate the regrowth of damaged retinal axons and, as a consequence, stimulate the axons to reenter their host target, the superior colliculus (SC). Fifteen to 581 days after transplantation, host retinal projections were traced by injecting the right eye with horseradish peroxidase (HRP). Parallel series of frozen brain sections were stained for HRP histochemistry, acetylcholinesterase, Nissl, or neurofibrils. At all ages studied, grafts survived and grew within the wound cavity; survival was better in the older animals. Most cortical grafts and a small number of tectal grafts filled the wound cavity and formed complete tissue bridges across the lesion. The majority of tectal grafts were attached to one or the other side of the lesion and were connected to the opposite lesion face by glial and connective tissue membranes that formed over the lesion site. In many animals that received tectal transplants, host retinal axons were traced growing into the grafts. Regenerating axons innervated specific, localized areas within the grafts, and it appeared that the axons retained the ability to recognize their appropriate target cells within the graft neuropil. Comparable ingrowth into cortical grafts was not observed. Optic axons were occasionally seen reentering the superficial layers of the host SC; however, compared to fetal tectal grafts, the density of host SC innervation was sparse. The implications of these data are discussed with regard to the possible use of fetal neural tissue grafts as reconstructive tissue bridges in the mammalian central nervous system.

Animals↗
PubMed1992

Diffusion imaging of the human brain in vivo using high-speed STEAM MRI.

This paper describes a new method for diffusion imaging of the human brain in vivo that is based on a combination of diffusion-encoding gradients with high-speed STEAM MR imaging. The single-shot sequence 90 degrees-TE/2-90 degrees-TM-(alpha-TE/2-STE)n generates n = 32-64 differently phase-encoded stimulated echoes STE yielding image acquisition times of 576 ms for a 48 x 128 data matrix. Diffusion encoding is performed during the first TE/2-interval as well as during each readout period. Phantom studies reveal a quantitative agreement of calculated diffusion coefficients with literature values. EKG triggering completely eliminates motion artifacts from diffusion-weighted single-shot STEAM images of human brain in vivo. While signal attenuation of the cerebrospinal fluid (CSF) is predominantly due to flow, that observed for gray and white matter results from diffusion. Evaluated diffusion coefficients yield (1.0 +/- 0.1) x 10(-5) cm2 s-1 for gray matter, (0.5 +/- 0.1) x 10(-5) cm2 s-1 for white matter with the diffusion encoding parallel to the main orientation of the myelin sheath of the neurofibrils, and (0.3 +/- 0.1) x 10(-5) cm2 s-1 for white matter and a perpendicular orientation. All studies were performed at 2.0 T using a conventional 10 mT m-1 gradient system.

Brain↗
PubMed1992

The morphology and connectivity of dissociated and reaggregated fetal tectal tissue transplanted to the midbrain of newborn rats.

Tectal tissue from E15 or E16 Wistar rat embryos was dissociated and reaggregated (DR) prior to transplantation on to the midbrain of newborn host rats. We wished to determine how complete disruption of the donor tissue (i) affected the subsequent morphological development of the grafts in the host brain, and (ii) whether this procedure affected the selectivity with which host retinal axons innervated target regions in the tectal transplants. Forty-three to 135 days after transplantation, host rats received binocular injections of wheatgerm agglutinin-conjugated horseradish peroxidase. After perfusion, frozen sections of the grafts and underlying host brainstem were cut and reacted with tetramethylbenzidine to identify retinal projections, or stained for either acetylcholinesterase (AChE), Nissl or neurofibrils. All host brains contained identifiable DR grafts. Each brain contained at least one large transplant and numerous smaller pieces of graft tissue. The fragmentation of DR grafts was greater than that seen in direct, undissociated tectal transplants; however the morphology of individual DR grafts was markedly similar to direct grafts. Of particular interest was the presence in DR grafts of localized, often oval or circular regions, that possessed high AChE activity and contained mostly small (5 to 10 microns) close-packed neurons. AChE-dense patches were found both superficially and deep within DR grafts and appeared identical to those seen in direct transplants. These regions are thought to be homologous to the superficial, retinorecipient layers of normal superior colliculus (SC) and it is likely that the formation of these localized areas resulted from the selective association of presumptive SGS neurons within the reaggregating neuropil. In almost all cases, host retinal input to DR grafts was confined to the localized AChE-dense patches, suggesting that despite the dissociation procedure, specific retinal innervation of regions containing at least some of the appropriate target cells was maintained in DR tectal grafts.

Acetylcholinesterase↗
PubMed1989

An immunohistochemical study of the primitive and maturing elements of human cerebral medulloepitheliomas.

Four examples of human cerebral medulloepithelioma were studied immunohistochemically with a panel of antibodies and antisera to neuronal and glial proteins. The tumors, in addition to primitive medullary epithelium, contained areas of neuroblastic, ganglionic, astrocytic, ependymoblastic and ependymal differentiation, and in one tumor, areas resembling polar spongioblastoma. Tumor cells throughout the primitive medullary epithelium displayed focal immunoreactivity for vimentin, glial fibrillary acidic (GFA) protein and for the neuron-associated class III beta-tubulin isotype. Neuroblasts showed immunoreactivity for the class III beta-tubulin isotype, microtubule-associated protein 2 and neuron-specific enolase. Immunoreactivity for neurofilament epitopes and synaptophysin was detected in areas of ganglionic differentiation and coincided with the demonstration of neurofibrils in Bielschowsky's silver impregnations. Vimentin was the only marker detected in ependymoblastic and ependymal rosettes or in areas of polar spongioblastoma, as well as in mesenchymal cells. The results indicate that, even in very primitive neoplastic neuroepithelium, immunocytochemical evidence of early commitment of some of the cells to a neuronal or glial lineage can be demonstrated. The neuron-associated class III beta-tubulin isotype appears to be one of the earliest markers indicative of neuronal differentiation in normal and neoplastic primitive neuroepithelium.

Adult↗
PubMed1978

Silver impregnation methods for reticulum fibers and reticulin: a re-investigation of their origins and specificity.

Maresch (1905) introduced Bielschowsky's silver impregnation technic for neurofibrils as a stain for reticulum fibers, but emphasized the nonspecificity of such procedures. This lack of specificity has been confirmed repeatedly. Yet, since the 1920's the definition of "reticulin" and studies of its distribution were based solely on silver impregnation technics. The chemical mechanism and specificity of this group of stains is obscure. Application of Gomori's and Wilder's methods to human tissues showed variations of staining patterns with the fixatives and technics employed. Besides reticulum fibers, various other tissue structures, e.g. I bands of striated muscle, fibers in nervous tissues, and model substances, e.g. polysaccharides, egg white, gliadin, were also stained. Deposition of silver compounds on reticulum fibers was limited to an easily removable substance; the remaining collagen component did not bind silver. These histochemical studies indicate that silver impregnation technics for reticulum fibers have no chemical significance and cannot be considered as histochemical technics for "reticulin" or type III collagen.

Connective Tissue Cells↗
PubMed1986

Intratumorous distribution of catecholaminergic clone cells of human neuroblastoma. A catecholamine fluorescence study.

The intratumorous distribution of catecholaminergic clone cells in 23 human neuroblastomas was studied using Falck-Hillarp's method, and the findings compared with the catecholamine (CA) content within the tumour. All the specimens contained elements with CA fluorescence, and the pattern of fluorescence was classified from the distribution of CA-positive cells and neurofibrils, as diffuse cellular (DC), diffuse fibrillary (DF), sporadic (S), clustered (C), island-shaped (I), and bundled (B). The strength of CA fluorescence of both cellular and fibrillary elements correlated well with the CA content within the tumour. In addition, all tumours of urinary VMA-negative cases also contained significantly larger amounts of CA than other, non-functioning, tumours in the paediatric age group. The results of this study suggest that firstly, the ratio of CA-positive cells to CA-positive neuronal processes is proportionately higher in the poorly-differentiated neuroblastomas and that secondly, even tumours negative for urinary VMA or HVA might be polyclonal and contain catecholaminergic elements.

Adrenal Gland Neoplasms↗
PubMed1991

Ubiquitination and abnormal phosphorylation of paired helical filaments in Alzheimer's disease.

The most characteristic cellular change in Alzheimer's disease is the accumulation of aberrant filaments, the paired helical filaments (PHF), in the affected neurons. There is growing evidence from a number of laboratories that dementia correlates better with the accumulation of PHF than of the extracellular amyloid, the second major lesion of Alzheimer's disease. PHF are both morphologically and biochemically unlike any of the normal neurofibrils. The major polypeptides in isolated PHF are microtubule-associated protein tau. Tau in PHF is phosphorylated differently from tau in microtubules. This abnormal phosphorylation of tau in PHF occurs at several sites. The accumulation of abnormally phosphorylated tau in the affected neurons in Alzheimer's disease brain precedes both the formation and the ubiquitination of the neurofibrillary tangles. In Alzheimer's disease brain, tubulin is assembly competent, but the in vitro assembly of microtubules is not observed. In vitro, the phosphate groups in PHF are less accessible than those of tau to alkaline phosphatase. The in vitro dephosphorylated PHF polypeptides stimulate microtubule assembly from bovine tubulin. It is hypothesized that a defect in the protein phosphorylation/dephosphorylation system is one of the earliest events in the cytoskeletal pathology in Alzheimer's disease. Production of nonfunctional tau by its phosphorylation and its polymerization into PHF most probably contributes to a microtubule assembly defect, and consequently, to a compromise in both axoplasmic flow and neuronal function. Index Entries: Alzheimer's disease; mechanisms of neuronal degeneration; neurofibrillary changes; paired helical filaments: biochemistry; microtubule-associated protein tau; abnormal phosphorylation; ubiquitination; microtubule assembly; axoplasmic flow; protein phosphorylation/dephosphorylation.

Alzheimer Disease↗
PubMed1988

Cultured fetal tectal tissue grafted to the midbrain of newborn rats: morphology of grafts and innervation by host retinal and cortical axons.

It has been shown previously that tectal tissue obtained from young embryos can be successfully transplanted to the neonatal rat brain. In the present study, tecta from E15 rat embryos were maintained as free-floating explants for 3-14 days in vitro (DIV) before being transplanted to the midbrain of newborn rats. We wished to determine how explant culture affected (i) graft survival, (ii) the subsequent morphological and histochemical development of tectal grafts and (iii) the specificity with which host retinal and cortical axons grew into and innervated the graft neuropil. Grafts were examined 6-40 weeks posttransplantation. Host retinal input was assessed by injecting the host eyes with either [3H]proline, horseradish peroxidase (HRP) or wheat-germ agglutinin conjugated HRP. The host cortical projection was examined using anterograde degeneration techniques. Frozen tissue sections were also stained for Nissl, neurofibrils or reacted for acetylcholinesterase (AChE). All 3 DIV and 7 DIV explants survived transplantation and many grew considerably in size within the host brain. 14 DIV grafts were smaller and were found in only 50% of host brains. The cellular organization, fibre architecture and pattern of AChE staining in cultured grafts was similar to that found in non-cultured tectal transplants. Furthermore, host retina and cortex projected into the grafts in a manner similar to their innervation of non-cultured tectal tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Ectopic class II major histocompatibility antigens in Hirschsprung's disease and neuronal intestinal dysplasia.

Although the etiology of Hirschsprung's disease and neuronal intestinal dysplasia remains obscure, both have histological abnormalities involving ganglion cells and neuronal elements. Searching for a common pathway that may inhibit normal maturation of neurogenic precursors, we examined the possible role of an immune mechanism in the maldevelopment of the enteric neural network. Six patients with Hirschsprung's disease were studied by comparing biopsy specimens from diseased colon with ones taken from proximal ganglionic colon in the same patients. These were similarly compared with colonic biopsy specimens from patients studied with chronic constipation or bowel removed at the time of operation for other disorders. Biopsies were taken from four other patients with neuronal intestinal dysplasia. Each was examined by hematoxylin & eosin staining, acetylcholinesterase histochemistry, and immunohistochemistry of major histocompatibility complex (MHC) class I and class II antigens. All rectal samples from Hirschsprung's disease patients exhibited elevated acetylcholinesterase histochemistry and absent ganglia to confirm the diagnosis. These findings were correlated with marked elevation of class II MHC in the aganglionic area, whereas the proximal normal ganglionic segments showed no elevation. Rectal biopsy specimens from patients with chronic constipation exhibited no such elevation. A similar elevation of class II MHC was detected in the mucosa and submucosa of all four patients with the rare neuronal intestinal dysplasia disorder whose diagnosis was confirmed by giant ganglia in Auerbach's plexuses, aberrant Meissner's ganglia in the lamina propria mucosa, and giant neurofibrils in the mucosa and submucosa. The correlation of elevated class II MHC in these two neuronal dysfunction disorders may indicate an underlying autoimmune mechanism as is seen in thyroiditis and insulin dependent diabetes mellitus.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy↗
PubMed1999

Occurrence of gamma-aminobutyric acid-transaminase activity in nerve fibers of human thymus.

The specific localization of gamma-aminobutyric acid-transaminase (GABA-t) in the thymus of young and elderly men was studied. Our results show a specific vascular localization of GABA-t in the human thymus, and deal with the amount and distribution of GABA-t and its changes with age. Samples of human thymus were harvested throughout of 12 autopsies in infants (n = 3), as well as young (n = 3), adult (n = 3) and elderly (n = 3) men. Histologic staining of the human thymus was performed with eosin-orange, while histologic staining of nerve fibers was performed with the Bodian method. Histochemical and biochemical demonstration of GABA-t, including protein dosage, was performed by the methods of Van Gelder and Jung, respectively. Finally, quantitative analysis of images was performed. Staining with eosin-orange reveals the micro-anatomical details of the thymic micro-environment. The Bodian method shows the nerve fibers and neurofibrils. Histochemical staining for GABA-t shows an increase of this enzyme with age and a marked localization in the nerve fibers of the thymus in infant, young, adult, and elderly men, as well as specific vascular localization of this enzyme. These biochemical data are in accordance with the histoenzymatic results and confirm all of our previous observations. Finally, quantitative analysis of images performed on slices let us confirm all the morphological changes induced by age. We can conclude that GABA is an inhibitory neurotransmitter of the human thymus, while GABA-t plays an important role in GABA metabolism.

4-Aminobutyrate Transaminase↗
PubMed1976

Olfactory esthesioneuroblastoma.

Esthesioneuroblastomas are malignant tumours, usually of slow, invasive growth and low metastatic rate. Skeletal destruction must be assumed to be common, but is often demonstrable only by tomographic sections. Clinically these tumours do not differ from others of the same site, so that the diagnosis has to be based upon the histological appearances. In the light microscope the presence of neurofibrils is considered a specific differential diagnostic factor against other small-cell malignant tumours in this region. There seems to be no basis for a morphological classification into previously described sub-groups, neither according to histogenetic, light, nor ultra-microscopic findings. The general degree of differentiation and the number of mitoses appear to be the main factors of prognostic significance. Combined irradiation and surgical excision is considered the best treatment.

Adult↗
PubMed1983

Olfactory neuroblastoma. A case report in an African child.

The case is described of an eight-year-old Nigerian boy who died from olfactory neuroblastoma which presented with nasal obstruction and epistaxis. Autopsy showed intracranial extension of the tumour into the frontal lobe, and histology revealed undifferentiated neuroblasts, forming rosettes in some areas and producing tangled neurofibrils in others. The histogenesis of the tumour and its diagnosis are briefly discussed.

Child↗
PubMed2006

René Couteaux (1909-1999) and the morphological identification of synapses.

During a historical research, we realized that René Couteaux (1909-1999) was the first histologist who stained the postsynaptic structure of the neuromuscular junction. By means of Janus Green B dye, he revealed the membranous 'subneural apparatus' related to the 'synaptic gutter'. Hence, he justified the use of the physiological term 'synapse' in histology. A few years later, Couteaux localized acetylcholinesterase activity on this subneural apparatus with a histo-enzymatic method. The histochemical staining confirmed his histological observations that the subneural apparatus of the muscle cells was distinct from the nerve terminal. Thus Couteaux not only supported Cajal's neuron theory, but also gave decisive morphological basis to the concept of the synapse, thought to be up to that time a physiological entity. These observations were performed several years before the first electron microscopic data obtained in the U.S.A. When the electron microscopy became available in Europe, Couteaux studied the ultrastructural details of the myoneural synapse. He found evidence for the presynaptic 'active zone' as a restricted zone of the thickened presynaptic membrane flanked on both sides with synaptic vesicles, some of which were observed to be opening into the synaptic cleft by exocytosis. Furthermore, the synaptic vesicles were shown to be displayed in two rows along the linearly prolonged active zone which is situated just above the 'trench-like' junctional folds of the muscle membrane. The discontinuity of the synaptic structure was confirmed by the three-dimensional observation of the intraneuronal network of neurofibrils with the first prototype of high-voltage electron microscope.

Acetylcholinesterase↗