Direct innervation of sensory fibers from the dorsal root ganglion of the cervical dura mater of rats

Sensory innervation of the dorsal longitudinal ligament and the meninges in the lumbar spine of the dog

Although intervertebral disc herniation is a well-known disease in dogs, pain management for this condition has remained a challenge. The goal of the present study is to address the lack of information regarding the innervation of anatomical structures within the canine vertebral canal. Immunolabeling was performed with antibodies against protein gene product 9.5, Tuj-1 (neuron-specific class III β-tubulin), calcitonin gene-related peptide, and neuropeptide Y in combination with the lectin from Lycopersicon esculentum as a marker for blood vessels. Staining was indicative of both sensory and sympathetic fibers. Innervation density was the highest in lateral areas, intermediate in dorsal areas, and the lowest in ventral areas. In the dorsal longitudinal ligament (DLL), the highest innervation density was observed in the lateral regions. Innervation was lower at mid-vertebral levels than at intervertebral levels. The presence of sensory and sympathetic fibers in the canine dura and DLL suggests that pain may originate from both these structures. Due to these regional differences in sensory innervation patterns, trauma to intervertebral DLL and lateral dura is expected to be particularly painful. The results ought to provide a better basis for the assessment of medicinal and surgical procedures.

Mast cells populations fluctuate along the spinal dura mater of the developing rat

The present study reveals developmental changes in the number, the phenotype and the distribution pattern of mast cells (MCs) along the cervical, the thoracic and the lumbar parts of the spinal dura mater. Postnatal infiltration of spinal dura by MCs does not appear to follow a sequential developmental pattern and meningeal MCs are unevenly distributed along the various parts of the examined dura. At each spinal level, areas most densely populated by MCs are the dorsal dura and the dural sleeves of the dorsal (sensory) spinal roots The developmental time course of the total MCs number is characterized by significant fluctuations in all three parts examined, with notable increases at P1, P4, P21 and P60 (peak value) for the cervical part, at P1 (peak value), P7 and P21 for the thoracic part and at P1, P7 (peak value) and P30 for the lumbar part. At P180, MCs number declines to 56%, 33% and 13% of the peak values for the cervical, the thoracic and the lumbar part, respectively. However, a different developmental pattern is followed by each subpopulation of MCs identified on the basis of their staining characteristics, namely connective tissue type mast cells (CTMCs), mucosal type or cells with characteristics of immature mast cells (MTMCs) and mixed type MCs, in each part examined. The findings may be of importance in elucidating physiological and pathological processes in the dura mater and the vertebral column.

The sensory and sympathetic nerve supply within the cervical spine: review of recent observations

The purpose of this review is to identify recently observed features of the sympathetic and sensory systems and their pathways which characterize cervical spine innervation and their potential relevance to the clinical pain syndromes. The results of studies examining the innervation patterns of the zygoapophysial joints serve to demonstrate that structures in the cervical spine, as in other spinal regions, are partly innervated by sensory nerves traveling along sympathetic pathways. These studies also demonstrate that the neuropeptide levels in the cell bodies located within the dorsal root ganglion of these sensory nerves fluctuate according to the physiological state of the zygoapophysial joint. Additional to the sympathetic nerves accompanying the vertebral artery, the innervation patterns of dura and posterior longitudinal ligament in the upper cervical spine are distinctive features of cervical spine innervation. The possible clinical implications of cervical innervation patterns are considered with reference to referred pain, the pain patterns associated with a dissecting vertebral artery and cervicogenic headaches.

Innervation and functional characteristics of connective tissues, especially elastic fibers, in human fetal thoracic intervertebral articular capsule and its surroundings

The articular capsules between the thoracic vertebrae, which have physiologically different functions from those of other levels of the vertebrae, have yet to be subjected to neuro-anatomical and fine structural analysis. In the present study, we analyzed serial frozen sections of decalcified thoracic vertebrae in human fetuses, and identified the articular capsule tissue with its unique distribution of elastic fibers. The fine structure of the elastic fibers was studied by transmission electron microscopy. In the early-stage fetus, the fibrous membrane forming the lateral intervertebral articular capsule contained abundant thin elastic fibers consisting of microfibrils. In the late-stage fetus, the lateral capsule of fibrous membrane was occupied by thick elastic fibers. A medial articular capsule, namely the ligamenta flava, contained numerous thick elastic fibers in both early and late-stage fetuses. The distributional differences in nerve fibers between early and late-stage fetuses were determined by immunostaining, using antibodies raised against protein gene product 9.5 (PGP 9.5; ubiquitin carboxyl-terminal hydrolase). Innervation by PGP 9.5 immunoreactive fibers was limited to the areas of the articular capsules near the blood vessels, which may indicate their functional relation with blood flow. No PGP 9.5 immunoreactive fibers were found in the ligamenta flava of the late-stage fetus. Innervation might be directly involved in the development of the intervertebral articular capsules in normal human fetuses.

Comparison of sensory and sympathetic innervation of the dura mater and posterior longitudinal ligament in the cervical spine after removal of the stellate ganglion

Although cervical spinal tissues are rich in sensory and sympathetic fibers, which play a significant role in clinical phenomena, there is little information available regarding their anatomical characteristics. In this study, we compared the innervation of the cervical dura mater and the posterior longitudinal ligament (PLL) to that after removal of the stellate ganglion to determine whether the anatomical background plays a significant role in clinical manifestations. Immunoreactivities for calcitonin gene-related peptide (CGRP) and substance P (SP) were used as sensory markers, and immunoreactivity for neuropeptide Y (NPY) was used as a sympathetic marker. Sensory fibers in the cervical dura mater were distributed within each cervical segment, but those in the PLL extended beyond the segmental borders. A dense sensory fiber network forming a single layer was seen at the intervertebral disc region in the cervical PLL, whereas sympathetic fibers in this region were sparsely distributed. Sympathetic fibers were distributed not only around the vascular wall but also in the region independent from vessels, and some occasionally ran together with sensory fibers in both the dura mater and the PLL. Removal of the stellate ganglion had little effect on the distribution of sensory fibers but denervated the sympathetic fiber networks in the region independent from vessels of the upper ipsilateral cervical PLL. In conclusion, the cervical dura mater and the PLL have different sensory and sympathetic innervations. Sympathetic fibers pass through the stellate ganglion to project to the region independent from vessels in the upper cervical PLL. Clinical symptoms may be attributed to this characteristic innervation of the cervical spine.

Catecholaminergic and acetylcholine esterase containing nerves of cranial and spinal dura mater in humans and rodents

The innervation of cranial and spinal dura mater in humans and rodents was studied by examining several dural zones (vascular, perivascular, intervascular) in different regions. Characterization and distribution of dural acetylcholinesterase-positive nerve fibers, catecholaminergic nerve fibers, and mast cells are analyzed and discussed. The results of chemical and surgical sympathectomy as well as the relationships between catecholaminergic nerve fibers and mast cells are studied. Our results are discussed in the light of possible implications in the physiopathology of dural algic syndromes including cephalalgia and spinal pain.

Nerve fibers innervating the cranial and spinal meninges: morphology of nerve fiber terminals and their structural integration

Pachymeninx and leptomeninx of cranial cavity and spine are considerably different in their collagenous fiber texture, cellular composition, vascularization, and innervation. The majority of meningeal nerve fibers terminate as free nerve endings whereas encapsulated and lamellated nerve terminals additionally occur in higher vertebrates including man. With respect to nerve fiber classification, arborization pattern, topography, and organization of the microenvironment at the termination site afferent and efferent nerve terminals are differentiated. Only the dura mater and the pial subcompartment of the leptomeninx possess the morphological prerequisites for neurogenic inflammation. In the current review, the results of morphological studies regarding the meningeal innervation including the sites of CSF (cerebrospinal fluid) production and absorption are discussed with emphasis on their structure-function relationships.