Electron microscopy of human peripheral nerves of clinical relevance to the practice of nerve blocks. A structural and ultrastructural review based on original experimental and laboratory data

ObjetivoEl principal objetivo fue describir la ultraestructura normal de los nervios periféricos y aportar todos aquellos aspectos relevantes para la práctica de los bloqueos anestésicos de los nervios periféricos.MétodoA partir de muestras de nervio ciático obtenidas de pacientes y muestras de saco dural, manguitos durales y nervios del plexo braquial disecados de cadáveres frescos se estudió la estructura del nervio periférico, incluyendo los fascículos y su composición topográfica, como así también la morfología de las cubiertas que revisten el nervio. Axones mielinizados, no mielinizados, fascículos, epineuro, perineuro y endoneuro fueron estudiados por microscopía óptica incluyendo métodos de inmunohistoquímica, y por microscopía electrónica de barrido y de transmisión. La estructura del perineuro, de los capilares intrafasciculares y su implicación en la barrera hematonerviosa fueron revisados.ResultadosCada uno de los elementos anatómicos fue analizado de forma individual, y los resultados fueron correlacionados con su impacto en la práctica clínica de la anestesia regional.ConclusionesLa práctica cotidiana de técnicas de anestesia regional y la visualización ecográfica de las estructuras nerviosas nos llevan a crear interpretaciones de la anatomía de los nervios cuyas repercusiones pueden ser importantes en la futura aplicación de la técnica. A este respecto, los resultados obtenidos en estudios ultraestructurales e histológicos están dirigidos a dar respuestas a esas dudas con origen en el entorno de las técnicas de la anestesia regional (AU)

AimThe goal is to describe the ultrastructure of normal human peripheral nerves, and to highlight key aspects that are relevant to the practice of peripheral nerve block anaesthesia.MethodUsing samples of sciatic nerve obtained from patients, and dural sac, nerve root cuff and brachial plexus dissected from fresh human cadavers, an analysis of the structure of peripheral nerve axons and distribution of fascicles and topographic composition of the layers that cover the nerve is presented. Myelinated and unmyelinated axons, fascicles, epineurium, perineurium and endoneurium obtained from patients and fresh cadavers were studied by light microscopy using immunohistochemical techniques, and transmission and scanning electron microscopy. Structure of perineurium and intrafascicular capillaries, and its implications in blood–nerve barrier were revised.ResultsEach of the anatomical elements is analyzed individually with regard to its relevance to clinical practice to regional anaesthesia.ConclusionsRoutine practice of regional anaesthetic techniques and ultrasound identification of nerve structures has led to conceptions, which repercussions may be relevant in future applications of these techniques. In this regard, the ultrastructural and histological perspective accomplished through findings of this study aims at enlightening arising questions within the field of regional anaesthesia (AU)

Electron microscopy of human peripheral nerves of clinical relevance to the practice of nerve blocks. A structural and ultrastructural review based on original experimental and laboratory data.

AIM: The goal is to describe the ultrastructure of normal human peripheral nerves, and to highlight key aspects that are relevant to the practice of peripheral nerve block anaesthesia. METHOD: Using samples of sciatic nerve obtained from patients, and dural sac, nerve root cuff and brachial plexus dissected from fresh human cadavers, an analysis of the structure of peripheral nerve axons and distribution of fascicles and topographic composition of the layers that cover the nerve is presented. Myelinated and unmyelinated axons, fascicles, epineurium, perineurium and endoneurium obtained from patients and fresh cadavers were studied by light microscopy using immunohistochemical techniques, and transmission and scanning electron microscopy. Structure of perineurium and intrafascicular capillaries, and its implications in blood-nerve barrier were revised. RESULTS: Each of the anatomical elements is analyzed individually with regard to its relevance to clinical practice to regional anaesthesia. CONCLUSIONS: Routine practice of regional anaesthetic techniques and ultrasound identification of nerve structures has led to conceptions, which repercussions may be relevant in future applications of these techniques. In this regard, the ultrastructural and histological perspective accomplished through findings of this study aims at enlightening arising questions within the field of regional anaesthesia.

Changes in the number and volume of NPY and VIP neurons from periprostatic accessory vegetative ganglia in pre- and peripubertal rats. A stereological study.

The amount of neurons of periprostatic accessory ganglia in pre- and peripubertal rats was studied to ascertain whether the development of these autonomic ganglia is androgen-dependent. Stereological estimates of the volumes and number of neurons immunoreactive to protein gene product 9.5 (PGP 9.5), neuropeptide Y (NPY), and vasoactive intestinal polypeptide (VIP) were carried out. Immunostaining of androgen receptors (AR) in the ganglia was also performed. The ganglionic neurons from the two groups studied were immunoreactive to PGP 9.5, NPY, and VIP. Almost all the neurons were immunostained for AR. The ganglionic volume showed a significant increase in peripubertal prostate in comparison with the prepubertal gland. No significant changes were observed with respect to the absolute number of neurons immunoreactive to all the antigens. The neuronal volume was significantly increased in peripubertal rats in comparison with prepubertal animals. These findings led us to the following conclusions: There is no evidence of neurogenesis during pubertal development in the periprostatic accessory ganglia of the rat. The increase of ganglionic volume in puberty is due to the growth in neuronal volume. There were no differences between the sizes of NPY and VIP neurons in pubertal periprostatic accessory ganglia. The development of periprostatic vegetative neurons is androgen-dependent.