Ultrastructure of dorsal root ganglia.

Dorsal root ganglia (DRG) contains thousands of sensory neurons that transmit information about our external and internal environment to the central nervous system. This includes signals related to proprioception, temperature, and nociception. Our understanding of DRG has increased tremendously over the last 50 years and has established the DRG as an active participant in peripheral processes. This includes interactions between neurons and non-neuronal cells such as satellite glia cells and macrophages that contribute to an increasingly complex cellular environment that modulates neuronal function. Early ultrastructural investigations of the DRG have described subtypes of sensory neurons based on differences in the arrangement of organelles such as the Golgi apparatus and the endoplasmic reticulum. The neuron-satellite cell complex and the composition of the axon hillock in DRG have also been investigated, but, apart from basic descriptions of Schwann cells, ultrastructural investigations of other cell types in DRG are limited. Furthermore, detailed descriptions of key components of DRG, such as blood vessels and the capsule that sits at the intersection of the meninges and the connective tissue covering the peripheral nervous system, are lacking to date. With rising interest in DRG as potential therapeutic targets for aberrant signalling associated with chronic pain conditions, gaining further insights into DRG ultrastructure will be fundamental to understanding cell-cell interactions that modulate DRG function. In this review, we aim to provide a synopsis of the current state of knowledge on the ultrastructure of the DRG and its components, as well as to identify areas of interest for future studies.

The Chick Embryo and Its Structures as a Model System for Experimental Ophthalmology.

The possibilities of using the chick embryo and its individual structures as a model system in experimental ophthalmology are considered. Cultures of the retina and spinal ganglia from chick embryos are used in the development of new methods for the treatment of glaucomatous optic neuropathy and ischemic optic neuropathy. The chorioallantoic membrane is used for modelling vascular pathologies of the eye, screening of anti-VEGF drugs, and assessing biocompatibility of implants. Co-culturing of chick embryo nervous tissue and human corneal cells makes it possible to study the processes of corneal reinnervation. The use of chick embryo cells and tissues in the "organ-on-a-chip" system opens up wide opportunities for fundamental and applied ophthalmological studies.

Phenotypical changes of satellite glial cells in a murine model of GM1 -gangliosidosis.

Satellite glial cells (SGCs) of dorsal root ganglia (DRG) react in response to various injuries in the nervous system. This study investigates reactive changes within SGCs in a murine model for GM1 -gangliosidosis (GM1 ). DRG of homozygous ß-galactosidase-knockout mice and homozygous C57BL/6 wild-type mice were investigated performing immunostaining on formalin-fixed, paraffin-embedded tissue. A marked upregulation of glial fibrillary acidic protein (GFAP), the progenitor marker nestin and Ki67 within SGCs of diseased mice, starting after 4 months at the earliest GFAP, along with intracytoplasmic accumulation of ganglioside within neurons and deterioration of clinical signs was identified. Interestingly, nestin-positive SGCs were detected after 8 months only. No changes regarding inwardly rectifying potassium channel 4.1, 2, 3-cyclic nucleotide 3-phosphodiesterase, Sox2, doublecortin, periaxin and caspase3 were observed in SGCs. Iba1 was only detected in close vicinity of SGCs indicating infiltrating or tissue-resident macrophages. These results indicate that SGCs of DRG show phenotypical changes during the course of GM1 , characterized by GFAP upregulation, proliferation and expression of a neural progenitor marker at a late time point. This points towards an important role of SGCs during neurodegenerative disorders and supports that SGCs represent a multipotent glial precursor cell line with high plasticity and functionality.

Phenotypical peculiarities and species-specific differences of canine and murine satellite glial cells of spinal ganglia.

Satellite glial cells (SGCs) are located in the spinal ganglia (SG) of the peripheral nervous system and tightly envelop each neuron. They preserve tissue homeostasis, protect neurons and react in response to injury. This study comparatively characterizes the phenotype of murine (mSGCs) and canine SGCs (cSGCs). Immunohistochemistry and immunofluorescence as well as 2D and 3D imaging techniques were performed to describe a SGC-specific marker panel, identify potential functional subsets and other phenotypical, species-specific peculiarities. Glutamine synthetase (GS) and the potassium channel Kir 4.1 are SGC-specific markers in murine and canine SG. Furthermore, a subset of mSGCs showed CD45 immunoreactivity and the majority of mSGCs were immunopositive for neural/glial antigen 2 (NG2), indicating an immune and a progenitor cell character. The majority of cSGCs were immunopositive for glial fibrillary acidic protein (GFAP), 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNPase) and Sox2. Therefore, cSGCs resemble central nervous system glial cells and progenitor cells. SGCs lacked expression of macrophage markers CD107b, Iba1 and CD204. Double labelling with GS/Kir 4.1 highlights the unique anatomy of SGC-neuron units and emphasizes the indispensability of further staining and imaging techniques for closer insights into the specific distribution of markers and potential colocalizations.

The Dorsal Root Ganglion as a Novel Neuromodulatory Target to Evoke Strong and Reproducible Motor Responses in Chronic Motor Complete Spinal Cord Injury: A Case Series of Five Patients.

OBJECTIVES: Current strategies for motor recovery after spinal cord injury (SCI) aim to facilitate motor performance through modulation of afferent input to the spinal cord using epidural electrical stimulation (EES). The dorsal root ganglion (DRG) itself, the first relay station of these afferent inputs, has not yet been targeted for this purpose. The current study aimed to determine whether DRG stimulation can facilitate clinically relevant motor response in motor complete SCI. MATERIALS AND METHODS: Five patients with chronic motor complete SCI were implanted with DRG leads placed bilaterally on level L4 during five days. Based on personalized stimulation protocols, we aimed to evoke dynamic (phase 1) and isotonic (phase 2) motor responses in the bilateral quadriceps muscles. On days 1 and 5, EMG-measurements (root mean square [RMS] values) and clinical muscle force measurements (MRC scoring) were used to measure motor responses and their reproducibility. RESULTS: In all patients, DRG-stimulation evoked significant phase 1 and phase 2 motor responses with an MRC ≥4 for all upper leg muscles (rectus femoris, vastus lateralis, vastus medialis, and biceps femoris) (p < 0.05 and p < 0.01, respectively), leading to a knee extension movement strong enough to facilitate assisted weight bearing. No significant differences in RMS values were observed between days 1 and 5 of the study, indicating that motor responses were reproducible. CONCLUSION: The current paper provides first evidence that bilateral L4 DRG stimulation can evoke reproducible motor responses in the upper leg, sufficient for assisted weight bearing in patients with chronic motor complete SCI. As such, a new target for SCI treatment has surfaced, using existing stimulation devices, making the technique directly clinically accessible.

Dorsal Root Ganglion Stimulation for Chronic Postoperative Pain Following Thoracic Surgery: A Pilot Study.

OBJECTIVES: Post-thoracotomy pain syndrome (PTPS) is defined as persistent pain following a thoracotomy and has an incidence of 21-61%. Dorsal root ganglion stimulation (DRG-S) is a form of neuromodulation that modulates pain signal transmission to the spinal cord. The aims of this study were to investigate the efficacy of DRG-S for the management of PTPS and to assess the role of thoracic paravertebral blocks (t-PVB) as a tool for prediction of success of DRG-S. MATERIALS AND METHODS: In this prospective study, we included all patients undergoing thoracic surgery, with PTPS not responding to pharmacotherapy and treated with DRG-S from September 2018 to February 2019. t-PVB followed by a percutaneous DRG-S trial was performed on all patients. Pain intensity was assessed through a numeric rating scale (NRS) and Douleur Neuropathique en 4 Questions (DN4) at baseline, post-trial, at 14 days, 90 days, and at one year after DRG-S implantation. Data summarized as continuous variables were expressed as means and standard deviations (SDs), and categorical variables were expressed as raw numbers and percentages. RESULTS: Four patients out of 51 who underwent thoracic surgery at our institution surveyed were included (mean age ± SD, 56 ± 16 years old). Mean NRS and DN4 were, respectively, 7.2 ± 0.96 SD and 8.2 ± 0.5 SD at baseline, 2.5 ± 0.6 SD and 3.2 ± 0.5 SD after t-PVB, 2.2 ± 0.5 SD and 2.2 ± 0.5 SD at 14 days, 90 days, and at one year after DRG-S implantation. No complications or side effects were reported. CONCLUSIONS: Our preliminary results show that DRG-S is an effective therapy for PTPS after thoracic surgery. In addition, thoracic paravertebral blocks performed prior to DRG-S correlated with a positive outcome with treatment.

Neurotrophic Effect of Magnesium Comenate in Normal and under Conditions of Oxidative Stress in Culture of Chicken Spinal Ganglia.

The neurotrophic properties of magnesium comenate were studied under standard conditions and under conditions of oxidative stress. It was found that magnesium comenate has a stimulating effect on the neurotrophic processes of the spinal ganglia under normal conditions and under conditions of oxidative stress. Under standard conditions, magnesium comenate exhibits neurotrophic activity at a concentration of 0.0001 mM, under conditions of oxidative stress, magnesium comenate exhibits neurotrophic activity at concentration 0.1 mM.

The Emerging Role of Spinal Dynorphin in Chronic Pain: A Therapeutic Perspective.

Notable findings point to the significance of the dynorphin peptide neurotransmitter in chronic pain. Spinal dynorphin neuropeptide levels are elevated during development of chronic pain and sustained during persistent chronic pain. Importantly, knockout of the dynorphin gene prevents development of chronic pain in mice, but acute nociception is unaffected. Intrathecal (IT) administration of opioid and nonopioid dynorphin peptides initiates allodynia through a nonopioid receptor mechanism; furthermore, antidynorphin antibodies administered by the IT route attenuate chronic pain. Thus, this review presents the compelling evidence in the field that supports the role of dynorphin in facilitating the development of a persistent pain state. These observations illustrate the importance of elucidating the control mechanisms responsible for the upregulation of spinal dynorphin in chronic pain. Also, spinal dynorphin regulation of downstream signaling molecules may be implicated in hyperpathic states. Therapeutic strategies to block the upregulation of spinal dynorphin may provide a nonaddictive approach to improve the devastating condition of chronic pain that occurs in numerous human diseases.

Microstimulation of afferents in the sacral dorsal root ganglia can evoke reflex bladder activity.

AIMS: Pudendal afferent fibers can be excited using electrical stimulation to evoke reflex bladder activity. While this approach shows promise for restoring bladder function, stimulation of desired pathways, and integration of afferent signals for sensory feedback remains challenging. At sacral dorsal root ganglia (DRG), the convergence of pelvic and pudendal afferent fibers provides a unique location for access to lower urinary tract neurons. Our goal in this study was to demonstrate the potential of microstimulation in sacral DRG for evoking reflex bladder responses. METHODS: Penetrating microelectrode arrays were inserted in the left S1 and S2 DRG of six anesthetized adult male cats. While the bladder volume was held at a level below the leak volume, single and multiple channel stimulation was performed using various stimulation patterns. RESULTS: Reflex bladder excitation was observed in five cats, for stimulation in either S1 or S2 DRG at 1 Hz and 30-33 Hz with a pulse amplitude of 10-50 µA. Bladder relaxation was observed during a few trials. Adjacent electrodes frequently elicited very different responses. CONCLUSIONS: These results demonstrate the potential of low-current microstimulation to recruit reflexive bladder responses. An approach such as this could be integrated with DRG recordings of bladder afferents to provide a closed-loop bladder neuroprosthesis.

Effectiveness of Dorsal Root Ganglion Stimulation in Chronic Pain Management: A Systematic Review.

OBJECTIVE: This systematic review aims to determine the effectiveness of dorsal root ganglion stimulation (DRGS) in chronic pain management. METHODS: In 2023, a comprehensive systematic review was undertaken utilizing various electronic databases, employing MeSH terms and free search terms tailored to the study's aims. This review included primary research such as cohorts, case-control studies, and clinical trials, all focusing on the efficacy of DRGS in treating various chronic pain conditions. Nonhuman or animal studies were omitted from the selection process. A review of study quality was conducted, followed by a meticulous analysis of the findings to synthesize the evidence. This review represents the most current research, with updates extending to 2024. A total of 400 articles were reviewed. Twenty-nine articles were included in our review after meticulous screening. RESULTS: Twenty-nine articles published in the last five years meeting selection criteria were identified, encompassing patients with various diagnoses warranting the use of DRGS beyond complex regional pain syndrome. Additionally, the analysis includes different outcome measurement tools, emphasizing improvements in pain management, functionality, and quality of life. Finally, common complications such as surgical site infections and issues with electrodes are highlighted. CONCLUSIONS: This systematic review affirms the effectiveness of DRGS therapy in managing diverse chronic pain conditions, highlighting improvements in quality of life, functionality, and mood states, making it a viable alternative for patients unresponsive to traditional treatments.

Herpes zoster peripheral nerve complications: Their pathophysiology in spinal ganglia and nerve roots.

Varicella zoster virus (VZV) causes chickenpox at the primary infection and then becomes latent in the spinal dorsal root ganglia; VZV can reactivate with aging, immunosuppression, stress, and other factors, occurring as herpes zoster (HZ) at 1-2 skin segments. HZ peripheral nerve complications caused by VZV reactivation include Hunt syndrome, segmental HZ paresis, post-herpetic neuralgia, and Guillain-Barré syndrome (GBS). We have encountered the rare HZ complications of upper-limb paresis, myeloradiculitis, and polyradiculoneuritis: an adult woman with upper-limb paresis consistent with the nerve root on segments above the thoracic HZ dermatome; another woman exhibiting ascending myeloradiculitis originating at the Th11-12 roots; an elderly woman with ascending VZV polyradiculoneuritis resembling GBS; an adult with VZV quadriplegia with disseminated HZ; and an elderly patient with VZV-associated polyradiculoneuritis. The three polyradiculoneuritis cases may be a new subtype of HZ peripheral neuropathy, but the pathophysiology for these HZ peripheral nerve complications unrelated to HZ dermatomes is unclear. We analyzed host factors, skin lesions, neurological and virological findings, and MRI results including 3D NerveVIEW in 15 Japanese patients treated at our facility for HZ peripheral neuropathy, including six differing from the HZ dermatome. Based on the clinical findings including MRI results of spinal ganglia and roots, we identified four possible routes for the patterns of VZV spread: (i) ascending spinal roots, (ii) ascending spinal cord, (iii) polyradiculopathy, and (iv) intrathecal spread. The incidence of HZ is increasing with the aging of many populations, and clinicians should be aware of these HZ neuropathies.

Lumbar safety triangle: comparative study of coronal and coronal oblique planes in 3.0-T magnetic resonance imaging.

Objective: To compare the measurements of the lumbar safety triangle (Kambin's triangle) and the invasion of the dorsal root ganglion in the triangle in coronal and coronal oblique planes. Materials and Methods: A cross-sectional study, in which 210 3.0-T magnetic resonance images of L2-L5 were analyzed in coronal and coronal oblique planes. Exams with lumbar spine anomalies were excluded. Demographic (sex and age) and radiological variables were recorded by a single evaluator. Results: Most sample was female (57.1%), mean age 45.5 ± 13.3 (18-98 years). The measurements average, as well as the areas, gradually increased from L2 to L5. The dorsal root ganglion invaded the triangle in all images. The safety triangle average area was smaller in the coronal oblique plane than in the coronal plane. Of the seven dimensions of safety triangle obtained for each level of the lumbar spine, six were significantly smaller in the coronal oblique plane than in the coronal plane. The only dimension that showed no difference was the smallest ganglion dimension. Conclusion: The dimensions and areas investigated were smaller in coronal oblique plane, especially the area (difference > 1 mm). The analysis of the triangular zone in this plane becomes important in the preoperative assessment of minimally invasive procedures.

Objetivo: Comparar as medidas do triângulo de segurança lombar (triângulo de Kambin) e invasão do gânglio da raiz dorsal no triângulo nas incidências coronal e coronal oblíqua. Materiais e Métodos: Estudo transversal, em que foram analisadas 210 imagens de ressonância magnética 3.0-T de L2-L5 nos planos coronal e coronal oblíquo. Foram excluídos exames com anomalias da coluna lombar. Variáveis demográficas (sexo e idade) e radiológicas foram registradas por um único avaliador. Resultados: A maioria da amostra era do sexo feminino (57,1%), com idade média de 45,5 ± 13,3 (18­98 anos). A média das medidas, assim como as áreas, aumentaram gradativamente de L2 a L5. O gânglio da raiz dorsal invadiu o triângulo em todas as imagens. A área média do triângulo de segurança foi menor na incidência coronal oblíqua do que na incidência coronal. Das sete dimensões do triângulo de segurança obtidas para cada nível da coluna lombar, seis foram significativamente menores no plano coronal oblíquo do que no plano coronal. Única dimensão que não apresentou diferença foi a menor dimensão do gânglio. Conclusão: As dimensões e áreas investigadas foram menores na incidência coronal oblíqua, especialmente a área (diferença > 1 mm). A análise da zona triangular nesta incidência torna-se importante na avaliação pré-operatória de procedimentos minimamente invasivos.

Dorsal root ganglia, neural crest migration, and spinal cord form in snakes.

The classic view of the vertebrate dorsal root ganglion is that it arises from trunk neural crest cells that migrate to positions lateral to the spinal cord, sending axons dorsally into the spinal cord and dendrites ventrally to meet with motor axons in the ventral root to form spinal nerves. As a result, the ganglion ends up lying in the dorsal root of the spinal nerve. Serial histological sections of parts of the trunk of juveniles of different snake species revealed that the ganglia lie distal to the junction of dorsal and ventral roots of spinal nerves and outside the neural canal. The anatomical position of spinal ganglia in snakes suggests that regulation of trunk neural crest migration in snakes differs from that in the model endotherms in which it has been most thoroughly explored. Dorsal roots have no distinct rootlets and the span of root entry to the spinal cord is short compared to that of ventral rootlets in the same segment. Comparing early developmental stages to juvenile spinal cords shows an increased separation of spinal nerve root sites and ventral migration of the ganglion in later development. Dorsal rami of the spinal nerves leave directly from the dorsal edge of the ganglion, and the ventral ramus leaves from the ventral tip of the ganglion. How these features relate to the developmental regulation of ganglion form and position and the extraordinary locomotor capabilities of the snake trunk are unclear.

Anatomical distribution of CGRP-containing lumbosacral spinal afferent neurons in the mouse uterine horn.

Sensory stimuli from the uterus are detected by spinal afferent neurons whose cell bodies arise from thoracolumbar and lumbosacral dorsal root ganglia (DRG). Using an in vivo survival surgical technique developed in our laboratory to remove select DRG from live mice, we recently quantified the topographical distribution of thoracolumbar spinal afferents innervating the mouse uterine horn, revealed by loss of immunoreactivity to calcitonin gene-related peptide (CGRP). Here, we used the same technique to investigate the distribution of lumbosacral uterine spinal afferents, in which L5-S1 DRG were unilaterally removed from adult female C57BL/6J mice (N = 6). Following 10-12 days recovery, CGRP immunoreactivity was quantified along the length of uterine horns using fluorescence immunohistochemistry. Relative to myometrial thickness, overall CGRP density in uterine tissues ipsilateral to L5-S1 DRG removal was reduced compared to the DRG-intact, contralateral side (P = 0.0265). Regionally, however, myometrial CGRP density was unchanged in the cranial, mid, and caudal portions. Similarly, CGRP-expressing nerve fiber counts, network lengths, junctions, and the proportion of area occupied by CGRP immunoreactivity were unaffected by DRG removal (P ≥ 0.2438). Retrograde neuronal tracing from the caudal uterine horn revealed fewer spinal afferents here arise from lumbosacral than thoracolumbar DRG (P = 0.0442) (N = 4). These data indicate that, unlike thoracolumbar DRG, lumbosacral spinal afferent nerves supply relatively modest sensory innervation across the mouse uterine horn, with no regional specificity. We conclude most sensory information between the mouse uterine horn and central nervous system is likely relayed via thoracolumbar spinal afferents.

Dorsal Root Ganglion Morphometric Changes Under Oxaliplatin Treatment : Longitudinal Assessment by Computed Tomography.

PURPOSE: Magnetic resonance neurography (MRN) can detect dorsal root ganglia (DRG) hypertrophy in patients with oxaliplatin-induced peripheral neuropathy (OXIPN) but is difficult to apply in clinical daily practice. Aims of this study were (i) to assess whether DRG volume is reliably measurable by routine computed tomography (CT) scans, (ii) to measure longitudinal changes in DRG during and after oxaliplatin administration and (iii) to assess correlation between DRG morphometry and individual oxaliplatin dose. METHODS: For comparison of MRN and CT measurements, CT scans of 18 patients from a previous MRN study were analyzed. For longitudinal assessment of DRG size under treatment, 96 patients treated with oxaliplatin between January and December 2014 were enrolled retrospectively. DRG volumetry was performed by analyzing routine CT scans, starting with the last scan before oxaliplatin exposure (t0) and up to four consecutive timepoints after initiation of oxaliplatin therapy (t1-t4) with the following median and ranges in months: 3.1 (0.4-4.9), 6.2 (5.3-7.8), 10.4 (8.2-11.9), and 18.4 (12.8-49.8). RESULTS: DRG volume measured in CT showed a moderately strong correlation with MRN (r = 0.51, p < 0.001) and a strong correlation between two consecutive CTs (r = 0.77, p < 0.001). DRG volume increased after oxaliplatin administration with a maximum at timepoint t2. Higher cumulative oxaliplatin exposure was associated with significantly higher absolute DRG volumes (p = 0.005). Treatment discontinuation was associated with a nonsignificant trend towards lower relative DRG volume changes (p = 0.08). CONCLUSION: CT is a reliable method for continuous DRG morphometry; however, since no standardized assessment of OXIPN was performed in this retrospective study, correlations between DRG size, cumulative oxaliplatin dose and clinical symptoms in future prospective studies are needed to establish DRG size as a potential OXIPN biomarker.

Cellular distribution of cannabinoid-related receptors TRPV1, PPAR-gamma, GPR55 and GPR3 in the equine cervical dorsal root ganglia.

BACKGROUND: The activation of cannabinoid and cannabinoid-related receptors by endogenous, plant-derived or synthetic cannabinoids may exert beneficial effects on pain perception. Of the cannabinoids contained in Cannabis sativa, cannabidiol (CBD) does not produce psychotropic effects and seems to represent a molecule having great therapeutic potential. Cannabidiol acts on a great number of cannabinoid and cannabinoid-related G-protein-coupled receptors and ionotropic receptors which have, to date, been understudied in veterinary medicine particularly in equine medicine. OBJECTIVES: To localise the cellular distribution of four putative cannabinoid-related receptors in the equine cervical dorsal root ganglia (DRG). STUDY DESIGN: A qualitative and quantitative immunohistochemical study. METHODS: The cervical (C6-C8) DRG of six slaughtered horses were obtained from a local slaughterhouse. The tissues were fixed and processed for immunohistochemistry, and the resulting cryosections were used to investigate immunoreactivity for the following putative CBD receptors: Transient receptor potential vanilloid type 1 (TRPV1), nuclear peroxisome proliferator-activated receptor gamma (PPARγ), and G protein-coupled receptors 55 (GPR55) and 3 (GPR3). RESULTS: Large percentages of neuronal cell bodies showed immunoreactivity for TRPV1 (80 ± 20%), PPARγ (100%), GPR55 (64 ± 15%) and GPR3 (63 ± 11%). The satellite glial cells (SGCs) were immunoreactive for TRPV1, PPARγ and GPR55. In addition, GPR55 immunoreactivity was expressed by DRG interneuronal macrophages. In addition, microglia cells were observed surrounding the neuron-SGC complex. MAIN LIMITATIONS: The limited number of horses included in the study. CONCLUSIONS: Cannabinoid-related receptors were distributed in the sensory neurons (TRPV1, PPARγ, GPR55 and GPR3), SGCs (TRPV1, PPARγ and GPR55), macrophages (GPR55) and other interneuronal cells (PPARγ and GPR55) of the equine DRG. Given the key role of DRG cellular elements and cannabinoid receptors in the pathophysiology of pain, the present findings provided an anatomical basis for additional studies aimed at exploring the therapeutic uses of non-psychotropic cannabinoid agonists for the management of pain in horses.

Tripeptidyl peptidase I activity in porcine lumbar spinal ganglia - a histochemical study.

Distribution of tripeptidyl peptidase I (TPPI) activity in the structures of porcine lumbar spinal ganglia (LSG) was studied by enzyme histochemistry on cryostat sections from all the ganglia using the substrate glycyl-L-prolyl-L-methionyl-5-chloro-1-anthraquinonyl hydrazide (GPM-CAH) and 4-nitrobenzaldehyde (NBA) as visualization factor. Light microscopic observations showed TPPI activity in almost all the LSG structures. The enzyme reaction in different cell types was compared semi-quantitatively. Strong reaction was observed in the small neurons, satellite ganglia cells and some nerve fibers. Weak reactivity was found in the large sensory somatic neurons, whereas moderate reaction for TPPI was determined in the middle sensory somatic neurons and some nerve fibers. Statistical analysis by one-way ANOVA showed no significance of difference (when p⟨0.05) for the number of TPPI positive neurons per mm2. The original data obtained by the enzyme histochemistry method give us a reason to presume that TPPI actively participates in the functions of all the neuronal structures in porcine LSG. According to our results, it could be suggested that TPPI activity is important for the functions of autonomic and somatic sensory neurons.

Lumbar safety triangle: comparative study of coronal and coronal oblique planes in 3.0-T magnetic resonance imaging / Triângulo de segurança lombar: estudo comparativo dos planos coronal e coronal oblíquo em ressonância magnética 3.0-T

Abstract Objective: To compare the measurements of the lumbar safety triangle (Kambin's triangle) and the invasion of the dorsal root ganglion in the triangle in coronal and coronal oblique planes. Materials and Methods: A cross-sectional study, in which 210 3.0-T magnetic resonance images of L2-L5 were analyzed in coronal and coronal oblique planes. Exams with lumbar spine anomalies were excluded. Demographic (sex and age) and radiological variables were recorded by a single evaluator. Results: Most sample was female (57.1%), mean age 45.5 ± 13.3 (18-98 years). The measurements average, as well as the areas, gradually increased from L2 to L5. The dorsal root ganglion invaded the triangle in all images. The safety triangle average area was smaller in the coronal oblique plane than in the coronal plane. Of the seven dimensions of safety triangle obtained for each level of the lumbar spine, six were significantly smaller in the coronal oblique plane than in the coronal plane. The only dimension that showed no difference was the smallest ganglion dimension. Conclusion: The dimensions and areas investigated were smaller in coronal oblique plane, especially the area (difference > 1 mm). The analysis of the triangular zone in this plane becomes important in the preoperative assessment of minimally invasive procedures.

Resumo Objetivo: Comparar as medidas do triângulo de segurança lombar (triângulo de Kambin) e invasão do gânglio da raiz dorsal no triângulo nas incidências coronal e coronal oblíqua. Materiais e Métodos: Estudo transversal, em que foram analisadas 210 imagens de ressonância magnética 3.0-T de L2-L5 nos planos coronal e coronal oblíquo. Foram excluídos exames com anomalias da coluna lombar. Variáveis demográficas (sexo e idade) e radiológicas foram registradas por um único avaliador. Resultados: A maioria da amostra era do sexo feminino (57,1%), com idade média de 45,5 ± 13,3 (18-98 anos). A média das medidas, assim como as áreas, aumentaram gradativamente de L2 a L5. O gânglio da raiz dorsal invadiu o triângulo em todas as imagens. A área média do triângulo de segurança foi menor na incidência coronal oblíqua do que na incidência coronal. Das sete dimensões do triângulo de segurança obtidas para cada nível da coluna lombar, seis foram significativamente menores no plano coronal oblíquo do que no plano coronal. Única dimensão que não apresentou diferença foi a menor dimensão do gânglio. Conclusão: As dimensões e áreas investigadas foram menores na incidência coronal oblíqua, especialmente a área (diferença > 1 mm). A análise da zona triangular nesta incidência torna-se importante na avaliação pré-operatória de procedimentos minimamente invasivos.

Quantitative models of feline lumbosacral dorsal root ganglia neuronal cell density.

BACKGROUND: Dorsal root ganglia (DRG) are spinal root components that contain the cell bodies of converging primary sensory neurons. DRG are becoming a therapeutic target for electrical neural interfaces. Our purpose was to establish methods for quantifying the non-random nature and distribution of neuronal cell bodies within DRG. NEW METHOD: We identified neuronal cell body locations in 26 feline lumbosacral DRG cross-section histological images and used computational tools to quantify spatial trends. We first analyzed spatial randomness using the nearest-neighbor distance method. Next we overlaid a 6×6 grid, modeling neuronal cellular density in each grid square and comparing regions statistically. Finally we transformed DRG onto a polar map and calculated neuronal cellular density in annular sectors. We used a recursive partition model to determine regions of high and low density, and validated the model statistically. RESULTS: We found that the arrangement of neuronal cell bodies at the widest point of DRG is distinctly non-random with concentration in particular regions. The grid model suggested a radial trend in density, with increasing density toward the outside of the DRG. The polar transformation model showed that the highest neuronal cellular density is in the outer 23.9% radially and the dorsal ±61.4° angularly. COMPARISON WITH EXISTING METHODS: To our knowledge, DRG neuronal cell distribution has not been previously quantified. CONCLUSIONS: These results confirm and expand quantitatively on the existing understanding of DRG anatomy. Our methods can be useful for analyzing the distribution of cellular components of other neural structures or expanding to three-dimensional models.

Neuronal differentiation in the developing human spinal ganglia.

The spatiotemporal developmental pattern of the neural crest cells differentiation toward the first appearance of the neuronal subtypes was investigated in developing human spinal ganglia (SG) between the fifth and tenth developmental week using immunohistochemistry and immunofluorescence methods. First neurofilament-200- (NF200, likely myelinated mechanoreceptors) and isolectin-B4-positive neurons (likely unmyelinated nociceptors) appeared already in the 5/6th developmental week and their number subsequently increased during the progression of development. Proportion of NF200-positive cells was higher in the ventral parts of the SG than in the dorsal parts, particularly during the 5/6th and 9/10th developmental weeks (Mann-Whitney, P = 0.040 and P = 0.003). NF200 and IB4 colocalized during the whole investigated period. calcitonin gene-related peptide (CGRP; nociceptive responses), vanilloid receptor-1 (VR1; polymodal nociceptors), and calretinin (calcium signaling) cell immunoreactivity first appeared in the sixth week and eighth week, respectively, especially in the dorsal parts of the SG. VR1 and CGRP colocalized with NF00 during the whole investigated period. Our results indicate the high potential of early differentiated neuronal cells, which slightly decreased with the progression of SG differentiation. On the contrary, the number of neuronal subtypes displayed increasing differentiation at later developmental stage. The great diversity of phenotypic expression found in the SG neurons is the result of a wide variety of influences, occurring at different stages of development in a large potential repertory of these neurons. Understanding the pathway of neural differentiation in the human, SG could be important for the studies dealing with the process of regeneration of damaged spinal nerves or during the repair of pathological changes within the affected ganglia. Anat Rec, 299:1060-1072, 2016. © 2016 Wiley Periodicals, Inc.