Appearance and distribution of neurofilament immunoreactivity in iris nerves

Noradrenaline levels rise significantly in rat arterial grafts at 6 hours postoperatively, and take 48 hours to come down

The aim of this study was to investigate the rate of disappearance of noradrenaline in arterial grafts after their transplanation. Arterial grafts were harvested from AO/Ks:OC strain rats. In each rat, a graft was harvested from the femoral artery and transplanted into the common carotid artery. A contralateral unoperated femoral artery served as control. High-performance liquid chromatography (HPLC) with electrochemical detection was used to determine the noradrenaline content in grafts and controls. Immediately after grafting, the noradrenaline content was 76% of control value, at 6 h 130% of control value, and at 48 h 4% of control value. The drop in graft noradrenaline content (from 0-48 h) was statistically significant (P = 0.005). The difference between 0-h, 12-h, and 24-h groups was statistically insignificant. Compared to control specimens, grafts contained less noradrenaline after 12 h, and it disappeared almost completely from femoral arterial grafts in rats within 48 h.

Immunohistochemical study of rabbit choroidal innervation

Immunocytochemical methods with antibodies to the light (68 kDa), medium (160 kDa), and heavy (200 kDa) chain subunits of the neurofilament triplet have been used to visualize neuronal structures in rabbit choroids. Choroidal nerve fibers were present in the suprachoroid and vascular laminae and absent in the choriocapillary layer. These fibers may be classified as perivascular and intervascular. Perivascular fibers surround all arterial and venous blood vessels and form a network; these fibers were labeled with the three NF antibodies, although they were more easily visualized with anti NF-160 and anti NF-200 than anti NF-68. Intervascular fibers formed two groups. The first group consisted of fibers situated between the blood vessels and parallel to the blood vessel wall surface (paravascular fibers); these fibers were better observed using anti NF-160 and NF-200 than anti NF-68. The second group consisted of fibers which travel the entire length of the choroid until they reach the nerve plexus of the ciliary body (long tract fibers). The plexus was observed with anti NF-68, anti NF-160 and anti NF-200; however, the long tract fibers were more clearly visualized with anti NF-160 and anti NF-200 than with anti NF-68. Two types of choroidal cell were also labeled: ganglion cells and melanocytes. Ganglion cells are small, scarce neurons situated in the peripheral choroid; they were labeled with anti NF-160 and anti NF-200. The melanocytes were only labeled with anti NF-200 and they were the only non neuronal structure visualized using antibodies against neurofilaments.

Perivascular nerves of the human basal cerebral arteries: I. Topographical distribution

In the present study the topographical distribution of the intrinsic nerve plexuses of the basal cerebral arteries in humans was quantified and the relation between vessel diameter and nerve density was investigated. Whole-mount preparations of various segments of the basal cerebral arteries from middle-aged patients were stained for protein gene product (PGP) 9.5. The deep nerve plexuses, located at the adventitial-medial border, were quantified by image analysis. Confocal scanning laser microscopy was used to study nerve plexuses throughout the adventitia. Transverse cryostat sections were stained for PGP 9.5, tyrosine hydroxylase and neurofilament, and quantified. The results showed a three-layered configuration of the adventitial nerves. Measurements on whole-mounts demonstrated that nerve densities were highest in the posterior communicating artery (PCom), and next highest in the proximal parts of the posterior cerebral artery (PCA) and anterior choroidal artery. There appeared to be no clear relation between nerve density and vessel diameter. The measurements on sections confirmed the high nerve densities in the PCom and PCA. Tyrosine hydroxylase- and neurofilament-immunoreactivities appeared to demonstrate separate subpopulations of the overall nerve plexuses, representing sympathetic and, possibly, sensory fibers, respectively. Densities of both subgroups generally followed those of PGP 9.5-immunoreactive nerves. Transmission electron microscopy suggested motor function of the deep nerve plexuses. The results indicate a stronger neuronal influence on this part of the cerebral circulation than hitherto reported. It is concluded that human basal cerebral arteries display a topographical distribution of deep perivascular nerves, and that nerve density is determined by locality rather than by vascular diameter.

Perivascular nerves of the human basal cerebral arteries: II. Changes in aging and Alzheimer's disease

In the present study the intrinsic nerve plexuses of the basal cerebral arteries, derived from aged non-Alzheimer's and aged Alzheimer's disease patients were quantified and compared. A previous study described and quantified nerve density on similar arteries from healthy middle-aged patients. Whole-mount preparations of various segments of the basal cerebral arteries were stained for protein gene product 9.5. The deep nerve plexuses, located at the adventitial-medial border, were quantified by image analysis. Transverse cryostat sections were stained for various markers and quantified. Measurements on whole mounts demonstrated that nerve densities were highest in the posterior communicating artery and in the postcommunicating part of the posterior cerebral artery (PCA) for both aged and Alzheimer's groups. Statistical comparison showed a tendency toward decreased nerve density with aging, which was significant for the internal carotid artery, precommunicating part of the PCA, and the anterior choroidal artery in both non-Alzheimer's and Alzheimer's aged groups. In addition, in Alzheimer's patients nerve density was significantly lower in the precommunicating part of the anterior cerebral artery compared with the healthy aged group. Measurements on sections confirmed the tendency to decreased innervation with aging. It is concluded that densities of deep perivascular nerves of human basal cerebral arteries are subject to localized changes caused by aging and Alzheimer's disease.

Influence of age and anti-nerve growth factor treatment on the sympathetic and sensory innervation of the rat iris

We have investigated alterations in the nerve supply to the iris of aged rats and the role of endogenous nerve growth factor in these changes. The overall density of nerve fibres, and the density of calcitonin gene-related peptide containing sensory nerves, were decreased by over 20% on the aged iris, as measured by computerized image analysis on immunostained preparations, while the density of sympathetic innervation was maintained. Whilst the majority of nerves supplying the iris (sympathetic, sensory and parasympathetic) are known to respond to exogenous nerve growth factor during development and in adulthood, the role of endogenous, target-derived nerve growth factor in nerve maintenance in maturity and old age awaits confirmation. Our results showed that localized treatment with anti-nerve growth factor of iridial nerve terminals did not affect sympathetic or sensory neurons in young rats, but caused a dramatic reduction of sympathetic nerve density on irides of old rats. The effect of anti-nerve growth factor treatment on the sensory innervation of old irides was less obvious. We conclude that aged sympathetic nerves are more susceptible to nerve growth factor deprivation than young ones, or than young or aged sensory neurons, perhaps as a result of reduced responsiveness to nerve growth factor with age. Since sympathetic innervation is maintained, whilst sensory innervation is decreased in the aged iris, age-related changes in innervation are unlikely to be due to altered availability of endogenous nerve growth factor.

RT97: a marker for capsaicin-insensitive sensory endings in the rat skin

The mouse monoclonal antibody RT97, which recognises the 200-kDa neurofilament subunit in its phosphorylated form, selectively labels the somata of sensory A-fibres (large light cells) in the dorsal root ganglion of the rat. We have tested the hypothesis that this antibody also visualises large diameter sensory fibres and their end structures in peripheral tissue, in particular in the skin. RT97 immunoreactivity is found in endings that are known to be served by myelinated afferent fibres, including Meissner-like endings, Merkel discs, hair follicle receptors, Pacinian corpuscles and free nerve endings. RT97 immunoreactivity has not, however, been observed in endings of presumably unmyelinated sensory fibres (intraepidermal fibres immunoreactive for substance P and calcitonin gene-related peptide) or in sympathetic fibres innervating sweat glands and blood vessels. In addition, neither systemic (100-150 mg/kg as adults) nor perineural capsaicin pre-treatment affects RT97 immunoreactivity in the skin. The data indicate that RT97 is a useful marker in the study of the capsaicin-insensitive sensory innervation of the skin and possibly other peripheral organs.

Experimental beta beta'-iminodipropionitrile (IDPN) neuropathy: neurofilament profile of sensory, motor and autonomic nerves as seen by immunocytochemistry on whole-mount preparations

IDPN-induced changes in a variety of sensory, motor and autonomic nerves were studied by whole-mount immunocytochemistry. A full range of proximo-distal accumulations of neurofilament-like material was found, from paranuclear round bodies in perikarya to distal and preterminal axonal dilations. Conversely, both terminal areas and nodal-paranodal regions of myelinated axons showed striking, sharply localized loss of neurofilament-immunostaining. The latter change, when transport of neurofilaments is halted by IDPN, may indicate their local processing and/or differential transport at nodal-paranodal regions.

Immunohistochemical studies of neurochemical markers in normal human buccal mucosa

The content of various substances, such as regulatory peptides, hormones and structural proteins, was investigated in normal buccal mucosa using indirect immunofluorescence. Thin nerve fibres, which from a morphological point of view were most probably sensory, showed immunoreactivity for substance P (SP), calcitonin gene-related peptide (CGRP), neuropeptide K (NPK) and neurokinin A (NKA). Also galanin (GAL), gamma-melanocyte stimulating hormone (gamma-MSH) and somatostatin (SOM) stained thin fibres were found in the propria, which were, however, few in number and the gamma-MSH staining was weak. CGRP, vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine amide (PHI) and neuropeptide Y (NPY) immunoreactive nerve fibres were observed in close connection to blood vessels. SOM positive cells with processes were found, mostly scattered, in the connective tissue. A population of cells within the epithelium also showed somatostatin immunoreactivity. Protein S-100 (S-100) stained distinct populations of cells at two separate locations. In the propria, cells with one or two slender processes were seen, being mostly single but sometimes forming groups. In the epithelium, dendritic cells with many processes with or without 'spines' were observed, mainly located to the basal layer of the lamina epithelialis. Single nerve fibres and nerve bundles were also stained. Neurofilament (NF) positive fibres, singly and in bundles, as well as endorgan-like structures were seen. Neuron-specific enolase (NSE) and protein gene product 9.5 (PGP 9.5) both stained the same structures, namely single fibres, nerve bundles, nerves surrounding vessels and innervating muscles and glands (if present in the section), as well as Merkel cells. Also with these two markers endorgan-like structures were seen. No clear innervation of the epithelium could be observed with the markers used. No methionine-enkephalin (ENK) or synaptophysin (SYN) immunoreactive material was found.

Chemoreceptor A-fibres in the human carotid body contain tyrosine hydroxylase and neurofilament immunoreactivity

Previous retrograde tracing studies on rat and guinea-pig showed a projection of sensory tyrosine hydroxylase-immunoreactive neurons to the region of the carotid bifurcation via the carotid sinus nerve. In the present study, focussing on the sensory innervation of the human carotid body, antisera to tyrosine hydroxylase and other catecholamine synthesizing enzymes were applied for an immunohistochemical investigation of carotid bodies obtained at autopsy. In addition, an array of antisera directed to non-enzyme antigens known to be present in viscero-afferent neurons were incorporated in the study. The glomic lobules consisting of glomus cells and sustentacular cells contained a variable number of enzyme-immunoreactive glomus cells. Arteries were supplied by nerve fibres displaying the full phenotype of sympathetic noradrenergic axons, i.e. immunoreactivity to tyrosine hydroxylase, aromatic-L-amino-acid-decarboxylase and dopamine-beta-hydroxylase. The glomic lobules, however, were densely innervated by tyrosine hydroxylase-immunoreactive axons lacking immunoreactivity to aromatic-L-amino-acid-decarboxylase and dopamine-beta-hydroxylase. These fibres reacted with neurofilament 160kD-antibody but were devoid of immunoreactivity to all neuropeptides tested (calcitonin gene-related peptide, somatostatin, substance P). Ultrastructurally, tyrosine hydroxylase/neurofilament 160kD-immunoreactive axons gave rise to large axonal swellings filled with mitochondria and vesicles, and established extensive contacts to glomus cells. Nerve bundles surrounded by a perineural sheath contained both myelinated (2.0-2.8 microns in diameter) and unmyelinated (0.14-3.0 microns) tyrosine hydroxylase-immunoreactive axons. Most of the unmyelinated immunoreactive axons were running singularly within a Schwann cell-sheath. Judged from the pattern of immunoreactivities as well as their preterminal and terminal ultrastructure, tyrosine hydroxylase-immunoreactive axons innervating glomus cells are of sensory origin. Although final proof by retrograde tracing cannot be presented in man, this conclusion is supported by experimental evidence in laboratory animals. The myelinated immunoreactive axons correspond to chemoreceptor A-fibres whereas the classification of the large unmyelinated immunoreactive axons has yet to be established. The lack of immunoreactivity to the dopamine-synthesizing enzyme, aromatic-L-amino-acid-decarboxylase, in this fibre type does not support the view of dopamine being the primary transmitter of chemoreceptor afferents.

Sensory innervation of human thoracolumbar fascia. An immunohistochemical study

We have studied the human thoracolumbar fascia by using antiserum against neurofilament protein (NFP) and S-100 protein to identify sensory nerve fibers and their endings. Seven surgical specimens from 7 patients were studied with light microscopy. In addition to free nerve endings, two types of encapsulated mechanoreceptors (Ruffini's and Vater-Pacini corpuscles) were identified. These findings support the hypothesis that the thoracolumbar fascia may play a neurosensory role in the lumbar spine mechanism.

Occurrence and distribution of different neurochemical markers in the human dental pulp

The occurrence and distribution of neuronal markers in human premolar and molar pulps were studied immunohistochemically. In the apical and central parts of the pulp, evenly distributed, thick neurofilament-immunoreactive nerve bundles predominated, which in many instances accompanied blood vessels. In the coronal parts, especially in the pulp horns, such nerve bundles formed a subodontoblastic plexus, while thin neurofilament-immunoreactive fibres projected into the odontoblastic region. In the coronal parts of the pulp, thin, varicose, calcitonin gene-related peptide (CGRP)- and occasionally substance P-immunoreactive fibres were observed in the pulp-dentine zone and also in the vicinity of blood vessels. Vasoactive intestinal polypeptide (VIP) fibres were distributed in several nerve bundles, while single VIP fibres were seen projecting into the odontoblastic region as well as in the vicinity of blood vessels. Peptide histidine isoleucine amide (PHI)-immunoreactive fibres showed a similar distribution as VIP, but were less common. Furthermore, neuropeptide Y-immunoreactive fibres occurred occasionally around blood vessels in the inner parts of the pulp. Tyrosine hydroxylase-immunoreactive nerve fibres with a varicose appearance were observed in some nerve bundles, but were also frequently seen around and in blood vessels. In premolar pulps obtained from teeth with open apices a less dense neurofilament innervation was seen in the coronal pulp. However, no apparent difference in the occurrence and distribution of the other neuronal markers was found compared to mature teeth. The human dental pulp, thus, seems to have a rich occurrence of neuropeptides and tyrosine hydroxylase in thin, varicose fibres. However, the distribution of the fibres expressing immunoreactivity to these neuronal markers seems to be sparse in comparison to neurofilament-immunoreactive fibres.

Immunohistological study of neuronal markers in inflamed gingiva obtained from children with Down's syndrome

The histological appearance of the gingiva in children with Down's syndrome (DS) was studied with special reference to inflammatory involvement and innervation. A dense infiltration of inflammatory cells was seen in the propria of most of the DS patients, including a few polymorphonuclear leucocytes. A hyperplasia of the epithelium was also found. The innervation of the gingiva was studied using immunohistochemistry. Nerve fibers as well as nerve bundles immunoreactive to neurofilament (NF) were seen in the propria, while occasionally intraepithelial NF fibers were observed. Calcitonin gene-related peptide (CGRP)-immunoreactive fibers and fiber bundles were also visualized, but they were less abundant than NF fibers. The density of NF and CGRP fibers and fiber bundles was estimated by semiquantitative evaluation. A higher density of NF and CGRP immunoreactive structures was observed in the propria of DS patients compared to the control subjects, while no obvious alteration was seen in their distribution in the propria. In addition, sparsely distributed fibers immunoreactive to peptide histidine isoleucine amide (PHI) and vasoactive intestinal polypeptide (VIP) fibers as well as neuropeptide Y (NPY) and tyrosine hydroxylase (TH) were seen, mainly surrounding blood vessels. A few substance P (SP) fibers were also found, mostly close to the epithelium. No obvious differences of these sparsely distributed fibers were seen in the DS patients compared to controls. Thus, a profound inflammatory involvement of the gingiva of DS patients is seen concomitant with a hyperinnervation of the presumed sensory component of the gingival innervation. In contrast, no alterations were seen in the density of neuronal markers related to autonomic nerve fibers. The sensory hyperinnervation observed is probably not specifically related to DS, but may be due to a sprouting of afferent nerves induced by the inflammatory reaction. However, factors released from the sensory afferents could contribute to the gingival inflammation seen in DS.

Neurofilament protein triplet immunoreactivity in the dorsal root ganglia of the guinea-pig

Immunoreactivity for the neurofilament protein triplet was investigated in neurons of the dorsal root ganglia of the guinea-pig by using a battery of antibodies. In unfixed tissue, nearly all neurons in these ganglia demonstrated some degree of neurofilament protein triplet immunoreactivity. Large neurons generally displayed intense immunoreactivity, whereas most small to medium-sized neurons showed faint to moderate immunoreactivity. Double-labelling immunofluorescence demonstrated that most antibodies to the individual subunits of the neurofilament protein triplet had the same distribution and intensity of labelling in sensory neurons. Increasing durations of tissue fixation in aldehyde solutions selectively diminished neurofilament protein triplet immunoreactivity in small to medium-sized neurons. Double-labelling with neurofilament protein triplet antibodies in combination with antibodies to other neuronal markers, such as neuron-specific enolase, substance P and tyrosine hydroxylase, showed that tissue processing conditions affect the degree of co-localization of immunoreactivity to the neurofilament protein triplet and to these other neuronal markers. These results indicate that, with a judicious manipulation of the duration of tissue fixation, neurofilament protein triplet immunoreactivity can be used in combination with other neuronal markers to distinguish groups of neurons according to their size and chemical coding.

Ultrastructural three-dimensional reconstruction of group III and group IV sensory nerve endings ("free nerve endings") in the knee joint capsule of the cat: evidence for multiple receptive sites

The noncorpuscular endings ("free nerve endings") of thinly myelinated group III and nonmyelinated group IV afferent nerve fibers have been examined in the knee joint capsule of sympathectomized cats by transmission electron microscopy and three-dimensional reconstruction of series of semi- and ultrathin sections. The sensory ending is the most distal part of a group III or IV nerve fiber that consists only of the sensory axon and associated Schwann cells but lacks a myelin sheath and is not surrounded by perineurium. The sensory axon divides into several branches and forms a terminal tree. The branches run either as single fibers or within small Remak bundles in parallel to sensory axons of other endings; they spread along vessel walls and also extend into dense connective tissue. Each sensory axon consists of a series of spindle-shaped thick segments ("beads") connected by waist-like thin segments. Thus all axons of sensory endings have a string-of-beads appearance, which resembles that of efferent sympathetic nerve fibers. The beads of the sensory axon and the end bulb at its tip show the same ultrastructural features which are characteristic of receptive sites: an accumulation of mitochondria and glycogen particles and various vesicles in the axoplasm and "bare" areas of axolemma that are not covered by Schwann cell processes. Group III and group IV sensory endings differ in the length of their branches (up to 200 microM in group III vs. more than 300 microM in group IV), number of beads per 100 microM axon length (about seven vs. nine or ten), mean diameter of axons (0.9-1.5 microM vs. 0.3-0.6 microM), and the presence of a neurofilament core consisting of bundles of parallel microfilaments only in group III. In conclusion, we propose that the sensory part of noncorpuscular "free nerve endings" is formed by the entire terminal tree of group III or group IV nerve fibers and that the beads in the course of the sensory axon represent multiple receptive sites.

Neurofilament protein-triplet immunoreactivity in distinct subpopulations of peptide-containing neurons in the guinea-pig coeliac ganglion

A battery of polyclonal and monoclonal antibodies raised against the triplet of identified neurofilament protein subunits was used to investigate neurofilament protein immunoreactivity in neurons of the guinea-pig coeliac ganglion. Using optimal conditions of fixation and tissue processing for each antibody we found that only 20% of the postganglionic sympathetic neurons in the guinea-pig coeliac ganglion contain neurofilament protein-triplet immunoreactivity. Double labelling with neurofilament protein-triplet antibodies raised in different species demonstrated that all of these antibodies labelled the same population of neurons. Double labelling using mouse monoclonal antibodies against neurofilament proteins in combination with rabbit polyclonals to neuronal markers showed that neurofilament protein-triplet immunoreactivity is restricted to specific chemically coded subpopulations of noradrenergic neurons. Approximately 52% of neurons in the ganglion contain neuropeptide Y and are presumed vasomotor neurons projecting to blood vessels in the submucosa of the small intestine. Virtually none of the neuropeptide Y-containing neurons were labelled with neurofilament protein-triplet antibodies. Neurons that contain somatostatin (21%) project to the submucous ganglia of the small intestine. Approximately two-thirds of neurons containing somatostatin are immunoreactive for the neurofilament protein-triplet. The other postganglionic neurons in the ganglion (27%) project to the myenteric plexus of the small intestine and do not contain either neuropeptide Y or somatostatin. Approximately a quarter of these neurons were labelled with neurofilament protein-triplet antibodies. These results suggest that the neurofilament protein-triplet may not be an intrinsic component of the cytoskeleton of all neurons. Furthermore the idea of a chemical coding of neurons should be extended to cytoskeletal proteins. The finding that these neurofilament proteins are confined to specific neuronal subpopulations has important implications for the search for a role of the neurofilament protein-triplet in neurons, for the interpretation of classical neurohistological silver impregnation techniques which appear to stain only neurofilament protein-triplet-containing neurons, as well as for neuropathological conditions that may involve these proteins in disease processes.

Immunohistochemical study of neurochemical markers in gingiva obtained from periodontitis-affected sites

Immunohistochemical methods have been used to study the occurrence of neuronal markers in human gingiva from periodontitis-affected sites. In periodontitis-affected buccal gingiva densely distributed neurofilament (NF)-immunoreactive (IR) fiber bundles were observed in the deeper parts of the propria, while NF-IR single fibers occurred in the superficial propria and occasionally in the buccal epithelium. Periodontitis-affected gingiva obtained from interproximal sites showed only sparsely distributed NF-IR fibers. Single nerve fibers immuno-reactive to the peptides substance P and calcitonin gene-related peptide occurred close to or within the epithelium in both buccal and interproximal gingiva. Around blood vessels neuropeptide Y-, peptide histidine-isoleucine amide- and vasoactive intestinal polypeptide-IR fibers were occasionally observed, while clusters of gamma-melanocyte-stimulating hormone-IR cells were found in the propria, in addition to gamma-melanocyte-stimulating hormone IR nerve fibers. Somatostatin-IR dendritic cells were seen in epithelium and propria of buccal and interproximal gingiva, although a high variability in the number of SOM-IR cells was observed. All neuronal markers studied showed a similar distribution in material obtained from young patients with clinically healthy gingivae, although the number of NF-IR fibers in the propria in these subjects was lower. The results demonstrate that in gingiva obtained from periodontitis-affected sites several different biologically active peptides occur in both nerve fibers and cells. At least some of these substances could possible play a role in the inflammatory process. However, since clinically normal gingiva was shown to contain nerve fibers and cells expressing immunoreactivity to the substances studied, no unique periodontitis-induced expression of the neuronal markers studied was found. Thus, any alteration of these substances during the periodontitis process remains to be elucidated.

Capsaicin treatment to developing rats induces increase of noradrenaline levels in the iris without affecting the adrenergic terminal density

The effects of administration of capsaicin to developing and adult Sprague-Dawley rats on substance P-containing primary afferent and peripheral adrenergic nerves were analysed by histochemical and neurochemical techniques. In control rats a relatively dense innervation with substance P-immunoreactive fibers was seen in the iris, while 10 weeks after a single neonatal injection of capsaicin (50 mg/kg s.c.) a moderate loss of substance P-immunoreactive nerve fibers was observed. The substance P level was decreased by 60%, while the noradrenaline level, 3H-noradrenaline uptake in vitro and the noradrenaline nerve density were unaltered. Repeated injections of capsaicin (2 x 50 mg/kg, 3 x 20 mg/kg s.c.) for 5 weeks to developing rats led to a very marked decrease of the substance P level and an almost complete disappearance of substance P-immunoreactive fibers in the iris, when analysed at 10 weeks of age. The noradrenaline level in the iris was significantly increased (+42%), while no significant changes in noradrenaline level were observed in heart auricula or superior cervical ganglion. The uptake in vitro of 3H-noradrenaline in irides and heart auriculae, as well as the noradrenaline terminal density in the dilator plate and surrounding blood vessels in the iris, were unaffected by repeated capsaicin treatment to developing rats. Capsaicin administration to adult rats (50 mg/kg s.c.), leading to a profound decrease in substance P, did not affect the noradrenaline levels at 24 hr after the injections. The results indicate that an extensive sensory denervation with capsaicin during development can induce an increase of noradrenaline levels in sympathetic nerve terminals in a target area (rat iris) with a rich SP-ergic sensory innervation, although the sympathetic terminal density is not influenced. Furthermore the increase in noradrenaline seems to require an extensive loss of SP-immunoreactive fibers and not solely a reduction of SP levels.

Localization of substance P and neurofilament immunoreactive fibers in the lumbar facet joint capsule and supraspinous ligament of the rabbit

An indirect immunofluorescence method was utilized to identify substance P-like immunoreactive (SPLI) and neurofilament protein immunoreactive (NFIR) fibers in the lumbar facet joint capsule and supraspinous ligament of the rabbit. The results demonstrated a large population of NFIR fibers, indicating that these tissues are richly innervated, and a smaller population of SPLI fibers. In some fibers, neurofilament protein and substance P were colocalized. The data suggest that the facet joint capsule and the supraspinous ligament contain SPLI nociceptive fibers that could be a source of low back pain.

Immunohistochemical study of neuronal markers in human gingiva with phenytoin-induced overgrowth

The immunohistochemical occurrence of several different neuronal markers has been investigated in human gingiva with phenytoin-induced overgrowth. The material was compared to gingival material taken following surgical orthodontic treatment. Gingiva obtained from the phenytoin-treated groups seemed to have a reduced number of neurofilament (NF) immunoreactive nerve fibers in the propria compared to control material. In both phenytoin as well as control gingiva sparsely distributed, thin, calcitonin gene-related peptide (CGRP) and substance P (SP) immunoreactive fibers were found in the propria. No obvious differences between the two groups could be observed for CGRP and SP. Immunoreactive cells for somatostatin (SOM) with a dendritic cell shape were found in the propria in both groups, sometimes in densely packed clusters. A tendency for increase of SOM-immunoreactive cells in the phenytoin-treated gingiva was observed. A few gamma-melanocyte stimulating hormone (gamma-MSH)-immunoreactive cells with a round appearance were found in control as well as phenytoin-affected gingiva. In one instance, however, a heavy gamma-MSH-immunoreactive cell infiltration was seen in the phenytoin sample. No immunoreactivity in either the phenytoin-treated group or in the control group was seen for proctolin or galanin. The results indicated that gingiva with phenytoin-induced overgrowth has a reduced innervation density revealed with NF immunohistochemistry.

2,5-Hexanedione-induced accumulations of neurofilament-immunoreactive material throughout the rat autonomic nervous system

In rats intoxicated with 2,5-hexanedione, nerve fibres supplying virtually all visceral organs showed large numbers of densely immunoreactive accumulations of neurofilament-like material, of fusiform, elongated, smoothly tapering morphology. In the gut, round to oval, morphologically different lesions were also present, and abnormal neurofilament-immunoreactive accumulations were revealed in oesophageal terminal end-plates. An extensive damage to autonomic nerve fibres, which are largely non-myelinated, was thus revealed in 2,5-hexanedione intoxication. The observed diversity in lesion morphology may suggest heterogeneity in cytoskeletal and/or associated proteins among autonomic neurons.

Innervation of periodontal ligament and dental pulp in the rat incisor: an immunohistochemical investigation of neurofilament protein and glia-specific S-100 protein

Nervous elements in the periodontal ligament and dental pulp of rat incisors were investigated by means of immunohistochemistry for neurofilament protein (NFP) and glia-specific S-100 protein. The periodontal ligament in the incisors was densely innervated by NFP-immunoreactive nerve fibers; the distribution of the nerve fibers and their terminations differed markedly from those in molars. NFP-positive, thick nerve bundles entered the lingual periodontal ligament through slits located in the mid-region of the alveolar socket, and immediately formed numerous Ruffini-like corpuscles. In the labial periodontal ligament, all of the NFP-immunoreactive nerve fibers terminated in free endings. The restricted location of the stretch receptor, Ruffini-like corpuscle, in the lingual periodontal ligament appears to be an essential element, because this region is regularly extended during mastication. The nervous elements were restricted to the alveolar half of the periodontal ligament in every region; they avoided the dental half of the periodontal ligament, which presumably moves continuously with the tooth. Pulpal nerve fibers in incisors also showed a characteristic distribution different from those in molars; individual nerve fibers with beaded structures ran in the center of the pulp toward the incisal edge, and did not form the subodontoblastic nerve plexus of Raschkow. Immunostaining for S-100 protein revealed a distribution pattern of nervous elements similar to that for NFP, suggesting that the nerves supplying the periodontal ligament and dental pulp were mostly covered by a Schwann sheath.

Ontogenetic development of the guinea pig uterine innervation. An immunohistochemical study of different neuronal markers, neuropeptides and S-100 protein

The ontogenetic development of the guinea pig uterine autonomic innervation was studied immunohistochemically using neurofibrillary protein (NF) and neuron specific enolase (NSE) as general neuronal markers, tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) as specific markers for adrenergic innervation and S-100 protein as marker for Schwann cell structure and/or function. In addition, comparisons were made of the development of the different populations of peptide-containing nerves. The structure and time of appearance were similar for nerves with NF-, NSE-, TH- and DBH-immunoreactivities, which were first present in the organ periphery as coarse nerve trunks, then extending centrally and branching into non-varicose nerves. From these, varicose nerves developed first in relation to vessels and then in association with the myometrial smooth musculature. Development was completed earlier in the cervix than in the uterine horns suggesting differences in local environment. In comparison, S-100 nerve-immunoreactivity appeared later but attained complete development more rapidly than axonal structures. Neuropeptide Y-immunoreactive nerves showed a similar developmental pattern to presumed adrenergic nerves, further verifying the assumption of intraneuronal localization of NPY in uterine adrenergic nerves. Other peptide-containing nerves were developed later probably reflecting differences in neuronal growth properties.

Neurofilament-like and glial fibrillary acidic protein-like immunoreactivities in rat and guinea-pig sympathetic ganglia in situ and after perturbation

The presence of neurofilament (NF)-like and glial fibrillary acidic protein (GFAP)-like immunoreactivities was studied in sympathetic ganglia of adult rats and guinea pigs during normal conditions and after perturbation. In the superior cervical ganglion (SCG) of normal rats, many ganglion cells and nerve fibers show NF immunoreactivity. Some of these nerve fibers disappear after preganglionic decentralization of SCG; this indicates the presence of a mixture of pre- and postganglionic NF-positive nerves in the ganglion. Cuts in both pre- and postganglionic nerves result in a marked increase in GFAP immunoreactivity in SCG, whereas NF immunoreactivity increases in nerve cell bodies after preganglionic cuts. Only a few ganglion cells show NF immunoreactivity in the normal SCG of guinea pig. All intraganglionic NF-positive nerves are of preganglionic origin; decentralization abolishes NF immunoreactivity in these nerve fibers. The inferior mesenteric ganglion, the hypogastric nerves and colonic nerves in guinea pigs contain large numbers of strongly NF-immunoreactive nerve fibers. When the SCG of adult rat is grafted to the anterior eye chamber of adult rat recipients, both ganglionic cell bodies and nerve fibers, forming on the host iris from the grafted ganglion, are NF-positive. As only the perikarya of these neurons normally exhibit NF immunoreactivity, and the terminal iris arborizations are NF-negative, it appears that the grafting procedure causes NF immunoreactivity to become more widespread in growing SCG neurons.

Distribution of nerve fibers immunoreactive to neurofilament protein in rat molars and periodontium

The distribution of nerve fibers in molars, periodontal ligament and gingiva of the rat shows a complex pattern. Decalcified material including the alveolar bone was sectioned in three different planes and stained by means of immunohistochemistry for detection of the neurofilament protein (NFP); the immunoreactive neural elements were clearly visualized in three-dimensional analyses. NFP-positive nerve fibers formed a subodontoblastic plexus in the roof area of the dental pulp; some of them entered the predentin and dentin directly through the dentinal tubules. This penetration was found mainly in the pulp horn, and was limited to a distance of about 100 micrometers from the pulpo-dentinal junction. In the periodontal ligament, NFP-positive nerve fibers were found densely distributed in the lower half of the alveolar socket. Two types of nerve terminals were recognized in the periodontal ligament: free nerve endings with tree-like ramifications, and expanded nerve terminals showing button- or glove-like shapes. The former tapered among the periodontal fibers, some even reaching the cementoblastic layer. The latter were located, frequently in groups, within the ligament restricted to the lower third of the alveolar socket. A well-developed plexus of NFP-positive nerves was revealed in the lamina propria of the free gingiva, the innervation being denser toward the epithelium of the gingival crevice. The characteristic distribution of NFP-immunoreactive nerve fibers revealed in this study is discussed in relation to region-specific sensations in the teeth and surrounding tissues.

Sensory reinnervation and sensibility after superficial skin wounds in human patients

In humans the innervation and sensibility after a superficial skin wound, the donor site for medium split thickness skin grafts, was investigated using sensibility tests and indirect immunohistochemistry with antibodies to neurofilament. After one to two weeks extensive sprouting of neurofilament immunoreactive nerve fibers was observed. Four weeks after the operation the wound had healed and the sensibility and distribution of neurofilament-positive nerve fibers resembled that of normal unoperated skin. These findings are discussed in view of recent studies indicating a role of sensory neurons in inflammation and wound healing.

Conjunctival nerve pathology in multiple endocrine neoplasia. A case report

A 31-year-old male with typical clinical features of multiple endocrine neoplasia type 2b (MEN 2b) was subjected to conjunctival biopsy. The patient had previously been operated for pheochromocytoma and medullary carcinoma of the thyroid. He came for ophthalmologic consultation because of redness and irritation of the eye due to dry eye syndrome. The conjunctival biopsy taken from his left eye revealed not only an increase in the number of conjunctival nerves but also an increase of their axons. The ultrastructure of the nerves was mostly normal, but the perineurium was often incomplete, and the interaxonal space appeared to be enlarged. Immunohistochemically, SP-, neurofilament- and, unexpectedly, leucine-enkephalin-positive nerve fibres were demonstrated in the conjunctival stroma. The rat is the only species in which enkephalin-like immunoreactivity has been described in the anterior segment of the eye. Thus, the presence of enkephalin-positive nerves in the conjunctiva of our MEN 2b patient may reflect a profound neural alteration.

N-myc and c-src genes are differentially regulated in PCC7 embryonal carcinoma cells undergoing neuronal differentiation

We examined the expression of N-myc, c-myc, and c-src in four embryonic carcinoma (EC) cell lines during different states of cell growth and following induction of in vitro differentiation. N-myc mRNA was detected in undifferentiated cells of four EC cell lines (PCC7, PCC3, PCC4, F9) neither of which showed N-myc gene amplification. No N-myc transcripts could be detected in mRNA prepared from a murine neuroblastoma cell line and from a murine fibroblast line. The level of N-myc mRNA decreased by 85% when PCC7 EC cells were induced by retinoic acid and cAMP treatment to form nerve-like cells. Six days after induction, the PCC7 cells changed into aggregates of neurofilament positive cells with massive neurite outgrowths. At this stage DNA replication had been reduced by more than 95%. The decreased N-myc expression in induced PCC7 cells was parallelled by 300-500% increase in c-src expression. Slowing of cell multiplication by serum starvation, on the other hand, did not affect the level of N-myc or c-src mRNA levels in PCC7 cells. C-myc was expressed in all EC lines except PCC7, which surprisingly did not express c-myc even at an exponential rate of proliferation. Chemical induction of F9 EC cells to form visceral endoderm or parietal endoderm resulted in markedly reduced (85%) levels of N-myc transcripts. A similar decline in c-myc expression was found in differentiated F9 cells. No c-src transcripts were detected in proliferating or differentiated F9 cells. These results suggest that N-myc may be expressed not only in neural development, but also in very early, undetermined embryonic cells. The activation of c-src expression when PCC7 EC cells differentiate into nerve-like cells shows that the pattern of proto-oncogene expression may change during a differentiation process, some proto-oncogenes increasing, others decreasing their representation in the mRNA pool.

Chromaffin cell heterogeneity of process formation and neuropeptide content under control and nerve growth factor-altered conditions in cultures of chick embryonic adrenal gland

Adrenal glands from embryonic day 11 (E-11) chicks were cryostat-sectioned, and it was determined that tyrosine hydroxylase-like immunoreactive (TLI) cells, somatostatin-like immunoreactive (SLI) cells, and methionine-enkephalin-like immunoreactive (ELI) cells occupied chromaffin regions of the gland. Similar age adrenals were dissociated, and the cells were cultured under serum-free conditions. Cultured TLI cells, ELI cells, and SLI cells were characterized according to cell size, cell number, and neurite formation. ELI and SLI cells composed two largely separate populations, with SLI cells tending to have larger cell areas, to be more numerous, and to be less likely to form neurites than ELI cells. The population of TLI cells, although unique in itself, was diverse and numerous enough to include all or portions of the neuropeptide-immunoreactive populations. Neurites of some cells from each of the above populations were strongly immunoreactive for alpha neurofilament protein, and for NAPA73 neurofilament-associated protein. However, neurites could also be observed in all populations that showed poor immunoreactivity for these cytoskeletal proteins. Exogenously added NGF significantly increased neurite-like process formation among TLI and ELI cells, but not among SLI cells. Reductions in the number of neurite-like processes following treatment with anti-nerve growth factor (NGF) were not significant for any of the populations. However, if shorter and broader process were included, anti-NGF caused a significant reduction in total cell processes among TLI and ELI cells. Anti-NGF inhibition of process formation among ELI cells could be reversed with exogenous NGF. Neither NGF or anti-NGF treatments showed a significant effect on cell numbers among TLI and ELI populations. The implications are that a compound of antigenic and physiological similarity to mouse salivary NGF is made by embryonic chick adrenal cells in culture, but the effects of NGF do not appear to be the same for all neural-crest-derived cells from the adrenal, and greater heterogeneity of phenotypes may exist among chromaffin cells than has previously been accepted. Some questions are also raised concerning the neurite-like nature of processes formed by some chromaffin cells in vitro.

Intermediate filaments in cultured human pleomorphic adenomas. An immunohistochemical study

Primary cultures of 9 benign human pleomorphic adenomas were analyzed by immunofluorescence and antibodies against the different intermediate filaments and microfilaments. The cultured cells were also cytogenetically characterized by G- and C-banding techniques. The adenoma cells expressed at least three different classes of intermediate filaments, viz. prekeratin, vimentin and glial fibrillary acidic protein (GFA). No correlation between chromosomal pattern and intermediate filament expression was found. The frequency of cells stained for each of the different antibodies varied considerably among the tumours. Prolonged culturing appeared to induce a reduction of cells positive for prekeratin. This was probably a true loss of antigens and not an effect of overgrowth of stromal cells. It is concluded that the cells studied, on the basis of several criteria, are of neoplastic origin. This in vitro system appears to be well suited for further histogenetic studies on pleomorphic adenomas.

Immature and mature neurofilament-immunoreactive trigeminal fibers can innervate the iris as studied by intraocular grafting of iris and trigeminal ganglia

Using immunohistochemistry on stretch-prepared whole mounts of adult rat irides, a dense, well-organized plexus of neurofilament-positive nerves originating in the trigeminal ganglion can be visualized. Such a two-dimensional tissue preparation is well-suited for studies on sensory and autonomic nerve fiber growth. In the present study the growth capacity of such neurofilament-positive nerves has been studied immunohistochemically. In irides homologously transplanted to the anterior eye chamber of adult albino rats, the intrinsic neurofilament-positive network had almost completely disappeared 4 days postoperatively. In whole mounts of iris grafts after 15 days and 4 weeks in oculo a gradually increasing plexus of nerves was observed. After 3.5 months in oculo a dense, regular network of fluorescent fibers had formed in the iris grafts to the same magnitude as in situ. However, whereas large axon bundles constituted a prominent feature of the distribution of neurofilament-positive nerves in situ, only a few and relatively thin axon bundles were seen in the grafts. The growth capacity of the neurofilament-positive trigeminal nerves was also studied by grafting fetal trigeminal ganglia to the anterior eye chamber. As visualized in cryostat sections, trigeminal grafts contained a large number of strongly fluorescent perikarya and a high density of positive fibers after intraocular maturation. Such grafts readily innervated the host iris. In the area immediately adjacent to the grafts, thin, parallel, rather weakly fluorescent fibers radiated out from the ganglia. When mature trigeminal grafts with attached host iris were regrafted to the anterior eye chamber of adult animals for a few days, in order to remove the intrinsic host iris innervation, such irides showed outgrowing fibers, often organized in small axon bundles, at long distances from the ganglion graft. The present report shows that both mature and immature neurofilament-immunoreactive neurons are capable of innervating the iris. Furthermore, this ingrowth can occur both in the presence and absence of normal intrinsic neurofilament-positive nerve fibers.

Ultrastructural and histochemical evidence for differentiation of intraocular locus coeruleus grafts and invasion of the host iris by central neurites and glia

Intraocular grafts of dorso-lateral pons, including the noradrenaline-containing cell group locus coeruleus, have been studied with ultrastructural and histochemical techniques. Also, the invasion of neuronal and glial constituents from the grafts into the iris of the host animal is described. In mature brain grafts, aggregates of locus coeruleus neurons were easily discernible with monoamine histofluorescence. These cells had an ultrastructural appearance very similar to that in situ. Numerous somatic spines were frequently associated with synaptic specializations, and monoamine-containing vesicles could be found scattered in the cytoplasm of the locus coeruleus cells. Large neurons of the nucleus tractus mesencephalici nervi trigemini were also found. These cells were neurofilament-immunoreactive just as in situ, and were ultrastructurally characterized by size, distribution of the granular endoplasmic reticulum and abundant large terminals in synaptic contact with their somata and processes. All grafts showed a vigorous astroglial proliferation, evidenced both with immunohistochemistry of glial fibrillary acidic protein and electron microscopy. The astroglial cells were more numerous, larger and with more processes than in adult in situ counterparts. At the attachment site of the brain stem grafts, the iris dilator plate was entirely changed ultrastructurally by a vigorous invasion of neuronal and astrocytic processes. The normal, loose connective tissue stroma of the iris was replaced by layers of almost exclusively central nerve fibres and astrocytes respectively. Monoamine histofluorescence demonstrated an extreme adrenergic hyperinnervation of the iris at the attachment site of the graft, compared to the normal sympathetic ground plexus, whereas neurofilament immunohistochemistry did not visualize any substantial ingrowth of such positive central nerve fibres. Immunohistochemistry of glial fibrillary acidic protein strongly supported the ultrastructural evaluation, showing profound astroglial invasion deep into the iris stroma. Electron microscopic identification of central nerve fibres in the iris showed numerous adrenergic locus coeruleus fibres with small dense-core vesicles. Also, bundles of thin, central, unmyelinated axons were found deep in the iris as well as occasional dendrites. Both large dense-cored and small clear vesicles were encountered in the iris fibres of brain graft origin. Axo-dendritic synaptic specializations formed by locus coeruleus-derived adrenergic fibres were found in the iris.(ABSTRACT TRUNCATED AT 400 WORDS)

Ultrastructural and histochemical studies of the rat iris: identified neuronal inputs and supportive glia

A detailed ultrastructural description was made of the rat iris with special emphasis on nerve fibre populations and their supportive glial cells. The location and identity of different autonomic (sympathetic and parasympathetic) and sensory nerves was further studied by monoamine histofluorescence, acetylcholinesterase histochemistry, immunohistochemistry for substance P and neurofilament, and Linder's silver staining. Schwann cells were defined with immunohistochemical techniques using antiserum to glial fibrillary acidic protein. By correlation of these morphological techniques, the relative proportion of different neuronal inputs and their glial constituents in various parts of the rat iris could be determined. The sympathetic and parasympathetic unmyelinated fibres showed the well-known preferential localization in the posterior part, approaching the smooth muscle cells and chromatophores in the dilator muscle. Larger arterioles in the anterior loose stroma of the iris were in close proximity to sympathetic fibres as indicated by monoamine histofluorescence. Sensory trigeminal nerves were visualized both with Linder's silver staining and neurofilament immunohistochemistry. Large myelinated axon bundles in the anterior part of the iris were clearly seen, and thin unmyelinated fibres were scattered throughout the anterior and posterior parts. Unmyelinated substance P-containing fibres were scattered preferentially in the anterior part of the iris, without close association with blood vessels. Distribution of supportive cells, indicated by means of immunofluorescence with antiserum against glial fibrillary acidic protein, appeared largely similar to that of neurofilament-positive nerve fibres. In the sphincter muscle, cholinesterase-positive nerve fibres were densely packed and adrenergic fibres as well as sensory, neurofilament- and substance P-containing fibres were sparse but distributed throughout the muscle. Accompanying glial cells positive for glial fibrillary acidic protein were also found.

Neurofilament and glial fibrillary acid protein-related immunoreactivity in rodent enteric nervous system

Using antisera raised against neurofilaments and the glial fibrillary acidic protein (GFAP) we have examined the appearance and distribution of neurofilament- and GFAP-like immunoreactivity in the enteric nervous system of rat, mouse and guinea-pig. In whole mounts of the external circular and longitudinal muscle layers, including the myenteric plexus, a high number of neurofilament-positive perikarya were visualized both in the ganglia and in the circularly running interconnecting strands in all three species. These cells were large, usually with eccentrically placed nuclei and single, relatively thick neurofilament-positive processes. In addition, in guinea-pig myenteric plexus a small number of cells with multiple processes could be seen. Both in the longitudinal and circular interconnecting strands a large number of thin, smooth, neurofilament-positive fibres were observed. This regular network of ganglia and strands was superimposed on a sparse system of thin, usually individual neurofilament-positive fibres in the underlying circular muscle layer. Cryostat sections revealed neurofilament-positive cell bodies in the submucous plexus, whereas fibres showing neurofilament-like immunoreactivity were observed in all layers of the gut wall, with the exception of the epithelium. In whole mounts including rat and mouse myenteric plexus, a large number of cells and fibres showing GFAP-like immunoreactivity were visualized. The GFAP-positive cells were smaller and more numerous than the neurofilament-positive ones. They were present both within the ganglia and in the interconnecting strands. Several short fluorescent processes could frequently be seen emanating from the cell body. Both the strands and the ganglia contained a high number of thin, GFAP-positive fibres. Fluorescent fibres and cells were also observed in the circular muscle layer. In sections of rat and mouse small intestine, cells were observed throughout the gut wall, with the exception of the epithelium. Double labelling experiments clearly showed that neurofilament- and GFAP-positive cells represented separate cell populations. Furthermore, GFAP-positive cells and fibres outlined the neurofilament-positive perikarya. It is thus likely that the GFAP-positive cells represent enteric glial cells. The pre- and postnatal development of neurofilament- and GFAP-like immunoreactivity was studied in whole mounts from rat embryos and pups. Furthermore, the presence of neurofilament and GFAP-positive fibres was observed in whole mount preparations of rat and mouse mesenterium.(ABSTRACT TRUNCATED AT 400 WORDS)

Enkephalin immunoreactivity in iris nerves: distribution in normal and grafted irides, persistence and enhanced fluorescence after denervations

The morphology and distribution of nerve fibers showing enkephalin-like immunoreactivity was studied in rat and mouse iris whole mounts. In adult rat, a relatively dense network of varicose fibers was seen throughout the iris. Individual, long, usually smooth fibers were observed running together with non-fluorescent fibers in bundles. Positive nerve fibers were also seen in the ciliary body and the choroid membrane. The fluorescence intensity was normally low. No enkephalin-positive fibers were detected in adult mouse iris. Extirpation or lesioning either one or all the three ganglia known to supply the rat iris with nerve fibers, the superior cervical, the ciliary and the trigeminal ganglia, caused no detectable decrease in amount of enkephalin-positive fibers. However, in irides grafted to the anterior eye chamber of adult recipients, no enkephalin-positive fibers could be observed 2-12 days postoperatively, strongly suggesting that degeneration of these fibers had occurred. When iris grafts were left longer in the eye, nerve fibers with enkephalin-like immunoreactivity reappeared. An increased fluorescence intensity was observed both in the ipsilateral and contralateral iris following extirpation or lesioning all three ganglia and in the ipsilateral iris after extirpation of the ciliary ganglion. Three days after a systemic injection of capsaicin, which causes a permanent disappearance of substance P fibers, the same phenomenon was often observed. This raises the possibility of an interaction between the enkephalin-positive and the substance P fiber systems in the iris.(ABSTRACT TRUNCATED AT 250 WORDS)

Masking of epitopes in tissue sections. A study of glial fibrillary acidic (GFA) protein with antisera and monoclonal antibodies

Antisera to chicken brain antigen (CBA) isolated by hydroxyapatite chromatography from 8 M urea extracts following repeated extractions with phosphate buffer selectively decorate neurofilaments (NF) in neuronal perikarya, dendrites and axons. The antisera also reacted with GFA protein, the astrocyte-specific intermediate filament protein, as indicated by the adsorption of NF immunoreactivity following passage of the antisera through columns prepared with purified GFA protein. Moreover, the antisera stained the polypeptides of the NF triplet (70 kd, 150 kd, 200 kd) and GFA protein by the immunoblotting procedure. Monoclonal antibodies selectively decorating NF in tissue sections were isolated from a fusion of mouse myeloma cells with spleen cells of mice immunized with CBA. By the immunoblotting procedure the antibodies decorated the 150 kd NF polypeptide and GFA protein. No staining of glial filaments or any other structure on tissue sections was also observed with antibodies derived from another fusion strongly reacting with GFA protein on immunoblots. All antibodies (monoclonal and polyclonal) appeared to react with the same region of the GFA polypeptide as indicated by immunoblots of cleavage products.

Distribution of neurofilament-immunoreactive nerve fibers in human skin

Neurofilament immunoreactive nerve fibers were demonstrated in human skin using indirect immunohistochemical technique with antibodies to neurofilament polypeptides. Neurofilament-positive fibers were seen as free nerve endings in the epidermis and in dermal papilla, in Meissner's corpuscles and as fibers crossing in the dermis. Strongly fluorescent nerve fibers were also seen around hair follicles, sweat gland ducts and sometimes in relation to blood vessels. From the distribution pattern it was concluded that predominantly sensory nerve fibers were labelled and that this technique may be used to study reinnervation of cutaneous sensory nerves following traumatic injuries and surgical procedures.