Quantitative analysis of the sympathetic innervation of the rat knee joint

Retrograde tracing with Fluoro-Gold (FG) was used to identify the complete population of knee joint sympathetic postganglionic efferents in the lumbar sympathetic chain of adult female Wistar rats. In 6 rats, the total number and distribution of FG-labelled neurons in the lumbar sympathetic chain was determined. The rat knee joint is supplied by an average of 187±57 sympathetic afferents with the majority at the L3 and L4 levels. Immunohistochemistry using antibodies specific for tyrosine hydroxylase (TH), somatostatin (SS) or vasoactive intestinal polypeptide (VIP) revealed that 33% of knee joint sympathetic afferents contained TH, 42% contained VIP, and none contained somatostatin. Retrograde tracing with FG provided accurate and reproducible labelling of the joint-innervating subpopulation of sympathetic efferent neurons. This model lends itself to the further study of the molecular responses of this neuronal population in the various disorders and conditions affecting joints.     

Adrenergic innervation of the capillaries

The sympathetic innervation of microvessels in the mesentery of the small intestine and the fibrous capsule of the kidney was studied by Falck's method in 20 dogs in which experimental cardiogenic shock was induced by six daily infusions of noradrenalin. Under these experimental conditions the sympathetic innervation of the capillaries and postcapillaries could be detected in these vacular regions.Central Research Laboratory, Central Postgraduate Medical Institute, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Fedorov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 1, pp. 48–49, January 1979.     

Sympathetic nerve distribution in human lymph nodes

Various lymph node functions are regulated by the sympathetic nervous system as shown in rodent studies. If human lymph nodes show a comparable neural regulation, their afferent nerves could represent a potential therapeutic target to treat, for example, infectious or autoimmune disease. Little information is available on human lymph node innervation and the aim of this study is to establish a comprehensive and accurate representation of the presence and location of sympathetic nerves in human lymph nodes. Since previous studies mention sympathetic paravascular nerves to occasionally extent into T cell-rich regions, the relation of these nerves with T cells was studied as well. A total number of 15 inguinal lymph nodes were resected from six donated human cadavers. Lymph node sections were stained with HE and a double T/B cell staining for evaluation of their morphology and to screen for general pathologies. A triple stain was used to identify blood vessels, sympathetic nerves and T cells, and, to study the presence and location of sympathetic nerves and their relation to T cells. To evaluate whether the observed nerves were en route to other structures or were involved in local processes, adjacent slides were stained with a marker for varicosities (synaptophysin), which presence is suggestive for synaptic activity. All lymph nodes contained sympathetic nerves, both as paravascular and discrete structures. In 15/15 lymph nodes, nerves were observed in their capsule, medulla and hilum, whereas only 13/15 lymph nodes contained nerves in their cortex. The amount of sympathetic nerves varied between compartments and between and within individuals. In general, if a lymph node contained more paravascular nerves in a specific compartment, more discrete nerves were observed as well. Occasionally, discrete nerves were observed in relation to T cells in lymphoid tissues of the cortex and medulla. Furthermore, discrete nerves were frequently present in the capsule and hilum. The presence of varicosities in a portion of these nerves, independently to their compartment, suggested a local regulatory function for these nerves. Human lymph nodes contain sympathetic nerves in their capsule, trabeculae, cortex, medulla and hilum, both as paravascular or as discrete structures. Discrete nerves were observed in relation to T cells and non-T cell-rich areas such as the hilar and capsular connective tissue. The presence of discrete structures suggests neural regulation of structures other than blood vessels, which was further supported by the presence of varicosities in a portion of these nerves. These observations are of relevance in further understanding neural regulation of lymph node immune responses and in the development of neuromodulatory immune therapies.     

Regional differences in innervation of lymph nodes in the Wistar rat

Previous light microscopic investigations have indicated that, in the rat, the innervation of mesenteric lymph nodes may be less dense than that of axillary nodes. However, nerves of the enteric system are difficult to visualise by light microscopy. Therefore we quantified the density of innervation of axillary and mesenteric lymph nodes at the ultrastructural level. The results show a highly significant difference in the density of innervation between these 2 groups of lymph nodes, but morphologically the type of the innervation does not seem to differ. In previous studies, nerves were found predominantly in regions characterised by aggregations of plasma cells. In view of this association, we suggest that the difference in innervation may reflect the migration of plasma cells out of mesenteric nodes and into the mucosa of the gut wall. By contrast, in peripherally located nodes, plasma cells tend to remain within the lymph nodes, and hence the density of innervation of these nodes is greater.     

Sympathetic innervation of human muscle spindles

The aim of the present study was to investigate the presence of sympathetic innervation in human muscle spindles, using antibodies against neuropeptide Y (NPY), NPY receptors and tyrosine hydroxylase (TH). A total of 232 muscle spindles were immunohistochemically examined. NPY and NPY receptors were found on the intrafusal fibers, on the blood vessels supplying muscle spindles and on free nerve endings in the periaxial space. TH‐immunoreactivity was present mainly in the spindle nerve and vessel. This is, to our knowledge, the first morphological study concerning the sympathetic innervation of the human muscle spindles. The results provide anatomical evidence for direct sympathetic innervation of the intrafusal fibers and show that sympathetic innervation is not restricted to the blood vessels supplying spindles. Knowledge about direct sympathetic innervation of the muscle spindle might expand our understanding of motor and proprioceptive dysfunction under stress conditions, for example, chronic muscle pain syndromes.     

Adrenergic and acetylcholinesterase-positive innervation of palatine tonsils in mammals

Innervation of human, feline and rabbit palatine tonsils was investigated. Adrenergic nerve components were visualized by formaldehyde-induced fluorescence of catecholamines and 5-HT, or by glyoxylic acid fluorescence, whereas acetylcholinesterase (AChE)-positive nerve structures were demonstrated by the direct thiocholine method. The largest density of adrenergic and AChE-positive nerve profiles was found in the adventitia of arterial branches in the fibrous capsula and septa, mainly in the form of periarterial nerve plexuses of different density. Fine nerve fibres lined the wall of small arteries which penetrated into extrafollicular lymphoid tissue and marginal layers of follicles. It is concluded that there are significant species-specific differences related to density, nature and topographic relations of adrenergic and AChE-positive nerve fibres in the various structural parts of palatine tonsils.     

Unmyelinated innervation of sinus hair follicles in rats

Unmyelinated nerve fibres comprise approximately one third of the innervation of rodent sinus hair follicles but their function is unknown. They may play a role as high-threshold sensory fibres, or may be autonomic efferents controlling the vascular sinus. In the present experiments capsaicin and surgical sympathectomy were used to establish whether these unmyelinated fibres are afferent fibres or autonomic efferents. The deep vibrissal nerves of mystacial follicles (C₁ and C₄) and a non-mystacial follicle (the postero-orbital, PO) were assessed in normal adult animals (n = 6) and compared with those treated with neonatal capsaicin (n = 6) or bilateral superior cervical ganglionectomy (n = 7). In capsaicin-treated animals, counts of fibres in the deep vibrissal nerves from all follicles showed normal numbers of myelinated axons, but approximately 80% reduction in unmyelinated fibres (normal mean ± SD: C₁ 94± 10, C₄ 89 ± 9, PO 85 ± 6; after neonatal capsaicin: C₁ 17 ± 8, C₄ 16 ± 6, PO 18 ± 6; n = 6, P < 0.001 for all follicles). After sympathectomy there was no significant reduction in myelinated or unmyelinated fibre numbers. Labelling of PO follicles with WGA-HRP showed minimal numbers of labelled cells (0–10) within the superior cervical ganglion, also suggesting minimal sympathetic innervation. This sparse sympathetic supply to the follicle was further demonstrated by a lack of tyrosine hydroxylase reactivity within the follicle complex; tissues outside the dermal capsule showed reactivity. It is concluded that most of the unmyelinated fibres entering sinus hair follicles are sensory in function. Moreover, the sparse autonomic innervation suggests minimal efferent control of the vascular sinus. Changes in vascular pressure are therefore unlikely to be a mechanism for regulating follicle sensitivity.     

The distribution of terminal sympathetic nerve fibers in bundle branches and false tendons of the bovine heart. An immunohistochemical and catecholamine histofluorescence study

Summary The sympathetic innervation in false tendons as a whole and the distribution of the terminal sympathetic nerve fibers in the conduction tissue in the bundle branches is unclear. Therefore, in the present study, false tendons and bundle branch regions of the bovine heart were examined using tyrosine hydroxylase (TH) immunohistochemistry and the glyoxylic acid induced catecholamine (CA) fluorescence method for demonstration of sympathetic nerve fibers. Acetylcholinesterase (AChE) histochemistry was also applied. Some of the nerve fascicles in the false tendons were found to contain large numers of sympathetic nerve fibers and such nerve fibers formed plexuses in the walls of arteries and arterioles in these structures. In both false tendons and bundle branches sympathetic nerve fibers 1) were non-homogeneously distributed in the conduction tissue, most regularly occurring in the channels of extracellular space that are present within the bundles of Purkinje fibres. and 2) showed the same pattern of distribution in relation to Purkinje fibre bundle surfaces as the AChE-positive nerve branches. The observations show that there is a substantial sympathetic innervation in false tendons. The final distribution of the nerve fibers in these structures and in the bundle branches are discussed in relation to what is known of tissue morphology and the occurrence of sympathetic nerve influences in these regions. In the present study, previous CA-fluorescence observations of a marked sympathetic innervation in bundle branch regions, in terms of the presence of sympathetic nerve fibers in nerve fascicles and vessel walls, were also corroborated by the application of TH-immunohistochemistry.     

Contribution of the cervical sympathetic ganglia to the innervation of the pharyngeal arch arteries and the heart in the chick embryo

In the chick heart, sympathetic innervation is derived from the sympathetic neural crest (trunk neural crest arising from somite level 10–20). Since the trunk neural crest gives rise to sympathetic ganglia of their corresponding level, it suggests that the sympathetic neural crest develops into cervical ganglia 4–14. We therefore tested the hypothesis that, in addition to the first thoracic ganglia, the cervical ganglia might contribute to cardiac innervation as well. Putative sympathetic nerve connections between the cervical ganglia and the heart were demonstrated using the differentiation markers tyrosine hydroxylase and HNK‐1. In addition, heterospecific transplantation (quail to chick) of the cardiac and trunk neural crest was used to study the relation between the sympathetic neural crest and the cervical ganglia. Quail cells were visualized using the quail nuclear antibody QCPN. The results by immunohistochemical study show that the superior and the middle cervical ganglia and possibly the carotid paraganglia contribute to the carotid nerve. This nerve subsequently joins the nodose ganglion of the vagal nerve via which it contributes to nerve fibers in cardiac vagal branches entering the arterial and venous pole of the heart. In addition, the carotid nerve contributes to nerve fibers connected to putative baro‐ and chemoreceptors in and near the wall of pharyngeal arch arteries suggesting a role of the superior and middle cervical ganglia and the paraganglia of the carotid plexus in sensory afferent innervation. The lower cervical ganglia 13 and 14 contribute predominantly to nerve branches entering the venous pole via the anterior cardinal veins. We did not observe a thoracic contribution. Heterospecific transplantation shows that the cervical ganglia 4–14 as well as the carotid paraganglia are derived from the sympathetic neural crest. The cardiac neural crest does not contribute to the neurons of the cervical ganglia. We conclude that the cervical ganglia contribute to cardiac innervation which explains the contribution of the sympathetic neural crest to the innervation of the chick heart. Anat Rec 255:407–419, 1999. © 1999 Wiley‐Liss, Inc.     

Common reactive erythrophagocytosis in axillary lymph nodes

Erythrophagocytosis by histiocytes in the sinuses of axillary lymph nodes is a common yet little-known phenomenon. The axillary lymph node dissections of 23 patients were studied by light microscopy and graded for the amount of erythrophagocytosis. None of the patients had evidence of a systemic hemolytic process. Nineteen of them exhibited some degree of erythrophagocytosis, and this was present even in four of the six patients who never had a prior breast biopsy. Breast biopsy was associated with massive degrees of erythrophagocytosis in 8 of 17 patients, and after a postbiopsy interval of two weeks 11 of 13 patients had hemosiderin deposition in the lymph nodes, evidence of red blood cell breakdown. This study serves to substantiate statements, made by others without confirmatory data, that large degrees of erythrophagocytosis may be seen in axillary lymph nodes after breast biopsies and that small amounts of erythrophagocytosis may be identified in lymph nodes of patients with no prior trauma history.     

A quantitative ultrastructural investigation of tyrosine hydroxylase-immunoreactive axons in the hairy skin of the guinea pig

Besides its thermoregulatory role, the sympathetic innervation of the skin is involved in a modulation of sensory processing and trophic functions that has not been fully characterized. To investigate possible sites at which such sympathosensory interactions might occur, a quantitative ultrastructural study of the sympathetic innervation of the skin was attempted. The hairy skin of the guinea pig was studied because the sympathetic and sensory nerve axons in this species can easily be discriminated by the presence of immunoreactivity to the catecholamine-synthesizing enzyme, tyrosine hydroxylase (TH). The thermoregulatory role of the sympathetic skin innervation was highlighted by the almost exclusive sympathetic innervation of piloarrector muscles which contained 62% (n = 195) of randomly selected TH-immunoreactive (TH-IR) axon profiles. Of TH-IR pilomotor axons, 53% were filled with vesicles. Vesicle-containing axonal profiles were equally frequent around dermal arterial blood vessels (partly associated with mast cells), hair follicles, and within nerve fibre bundles surrounded by a perineural sheath, in each case accounting for about 3% of all dermal TH-IR axonal profiles. In contrast to piloarrector muscles, at these locations TH-IR (sympathetic) and non-reactive (sensory) axons were found in close association. These findings are in line with the previously reported inhibitory influence of sympathetic stimulation upon hair follicle afferents and perivascular sensory nerve terminals. In addition, they point to a yet underestimated target of sympathetic axon terminals, i. e. preterminal nerve fibre bundles.     

Origin of sympathetic and sensory innervation of the knee joint

Summary The origin of sympathetic and sensory innervation of the knee joint was investigated by the intra-axonal transport method. After injection of horseradish peroxidase (HRP) or horseradish peroxidase conjugated to wheat germ agglutinin (WGA-HRP) into the knee joint unilaterally in adult rats, labelled neurons were found ipsilaterally both in sympathetic and dorsal root ganglia at the lower thoracic and lumbosacral levels. A maximum of 1500 and 1000 peroxidase-positive cells were observed in the sympathetic and dorsal root ganglia, respectively; in the former they were mainly located at the levels of L2–L4, and in the latter mainly at L3–L5. The functional implications of the above observations are discussed in relation to pain mechanisms in joints and to the earlier hypothesis that a nervous component might be involved in the pathogenesis of chronic joint inflammation.     

Studies on the reactive process in lymph nodes

Summary By means of a lengthy method of continuous cytologic and histologic study, an experimentally produced reactive process in lymphnodes was analyzed. This analysis was made both qualitatively and quantitatively, in an attempt to clarify the mechanisms of reaction and the underlying cellular alterations producing this change.The reaction begins in the medullary cords and gradually spreads to the cortex. New cells are formed. This cytopoesis, considered accidental, quantitatively exceeds the physiologic process, and depends upon stimulation of the reticulo-cellular system.The cells of this accidental cytopoesis are characteristically very variable in form. A constant transition of forms occurs. This dynamic cell, as it is seen in the reactive formation of new cells, can be observed only by continuous study. The small reticulum cell proves to be a particularly adaptable and plastic element, and is the real basis of the reaction. Large and small lymphocytes, as well as transitional forms and plasma cells are derived from it. For these cell types, no other parent cells can be postulated.The reactive formation of new cells reaches its maximum between the 20th and 26th day, and then shows a steady decrease in spite of further stimulation of the lymphnode. During the course of the reaction numerous quantitative interrelationsships among the individual groups of cells can be found. The conclusions gained from the cellular preparations are substantiated by means of histological controls and supplemented by a few important other points.The observation of the cytologic and histologic cellular movements, of the quantitative interrelationships among the individual groups of cells, and of the continuous change in form of the cells during the reaction are made the basis for the survey of the cytopoesis in lymphatic tissue. The large reticulum cell is considered to be the parent cell for the accidental formation of cells in reactive processes. The cellular supply is maintained probably by means of hemihomo-hemiheteroplastic reproduction. The small reticulum cell with the highest mitotic rate apparently reproduces itself in the homoplastic way. Those cells derived from it are responsible for the polymorphous picture of cells in the reactive processes of the lymphatic tissue. The theories of determinate developmental processes and the retrograde transformation of cells in lymphatic tissues are rejected.Both the bud-like formations on the nuclei of the small reticulum cells, and the appearance of dwarfed nuclei, in conjunction with the quantitative relation to the number of binucleated reticulum cells, suggest a mechanism of growth which shows similarity to the karyonomia or meroamitosis.     

Ontogeny of human intrahepatic innervation

Intrahepatic nerves serve important metabolic, sensory and motor functions. Their ontogeny in human liver has not been elucidated. We aimed to characterise the ontogeny of human intrahepatic innervation, to assess its relationship with biliary structures and to examine the distribution and nature of peptidergic nerves during development. We used immunohistochemistry on archival normal human liver tissue from 63 fetuses [8–40 gestational weeks (gw)] and 10 adults with antibodies to pan-neural markers and neuropeptides. Few nerve fibers appeared in portal tracts at 8 gw. Their density increased gradually from 12 gw and reached adult levels at 32–33 gw. Rare intra-acinar nerves, restricted to periportal areas, appeared at 40 gw. Galanin-, somatostatin- and calcitonin-gene-related peptide-positive nerve fibers were noted only in portal tracts from 22, 26 and 32 gw, respectively. In human adult liver, dense portal and intra-acinar neural supply was observed. Human fetal liver contains a neural network distributed mainly in portal tracts with a density that increases progressively towards term. Intra-acinar innervation appears at term, suggesting that is not required for normal liver function during development, while peptidergic nerves are important for intrauterine liver functions. Developmentally regulated expression of galanin and somatostatin may play a role in liver morphogenesis.     

The distribution of immunoglobulin and other plasma proteins in human reactive lymph nodes

The distribution of immunoglobulin, transferrin and albumin in human reactive lymph nodes was determined by the unlabelled antibody peroxidase-antiperoxidase (PAP) method and correlated with the structure of the nodes. All the nodes contained secondary lymphoid follicles which showed polarity towards a lymph sinus, usually the marginal sinus. The lymphatic sinuses were usually dilated. Various types of reticulum cells were demonstrated effectively by the metalophil method. Intracellular and extracellular antigen was well shown in paraffin sections of tissues fixed in buffered formaldehyde containing 5 per cent. acetic acid but cryostat sections were superior for surface Ig. The lymphocyte corona of each follicle reacted for surface immunoglobulin (μ, α, δ κ and λ chains). A polyclonal population of immunoglobulin-containing cells (centrocytes, centroblasts and plasma cells) was present in the follicle centre and numerous plasma cells were often found in the interfollicular areas; each of these cells contained one heavy and one light chain. The many other sites that reacted for immunoglobulin contained not only several heavy chains and both light chains but also transferrin and albumin: these sites included lymphocyte-like cells in the interfollicular areas; histiocytic, dendritic and fibroblastic reticulum cells; clusters of lymphocytes associated with dendritic reticulum cells; clusters of lymphocytes associated with dendritic reticulum cells; the cells lining the lymphatic sinuses and the intrasinusoidal reticulum cells; endothelial cells of the high endothelial venules; “extracellular” material in the germinal centres. The lymphatic endothelium and intrasinusoidal reticulum cells differed from the other sites, however, in reacting strongly for α and J chain and very weakly for γ chain. The fact that in reactive lymphoid tissue many cells contain several plasma proteins makes it difficult to draw conclusions about the role that such cells may have in the immune system. The morphological structure and immunohistochemical findings in ractive nodes are contrasted with the findings in lymphomas.