RESUMEN
Sympathectomy has been shown to induce resorption within the membranous middle ear bone of gerbils. It is unknown whether sympathectomy exerts a similar effect on endochondral long bone. In the present study, guanethidine sulfate (GS) and 6-hydroxydopamine (HDA) were administered to gerbils to induce sympathectomy. One week later, samples of middle ear bulla bone and radial long bone were harvested and assessed for osteoclastic activity. Histomorphometric analysis showed both pharmacologic sympathectomy with GS and chemical sympathectomy with HDA significantly increased the osteoclast counts and osteoclast surfaces of bulla bone samples but not radial long bone samples, respectively. In contrast, HDA but not GS increased the osteoclast profile area of both long bone and membranous bone samples when compared with vehicle-treated controls. Sympathectomy, induced both chemically and pharmacologically, thus has been shown to increase resorption in membranous bone but not endochondral long bone in the gerbilline model.
Asunto(s)
Remodelación Ósea/fisiología , Huesos/inervación , Osteoclastos/fisiología , Animales , Remodelación Ósea/efectos de los fármacos , Osículos del Oído/inervación , Osículos del Oído/fisiología , Gerbillinae , Guanetidina/farmacología , Masculino , Osteoclastos/citología , Osteoclastos/efectos de los fármacos , Oxidopamina/farmacología , Simpatectomía QuímicaRESUMEN
The length and complexity of the anatomical course of the facial nerve explains the difficulty of its accurate morphologic evaluation. CT and MR appear to be complementary techniques to precisely depict the nerve from its pontine origin to the parotid gland. Anatomical variations exist in length or thickness of all intrapetrous segments or as frequent dehiscences which can lead to false positive results or at the opposite falsely negative diagnoses. Close relations with the antero-inferior cerebellar artery in the intracisternal and intracanalicular segments must be known. Gadolinium enhancement is usual in the fallopian canal with variable intensity and thickness and should be differentiated from pathological enhancement. Finally the intrapetrous course of the chorda tympani can be precisely displayed on CT in the intra-osseous canal and in the middle ear near the ossicles.
Asunto(s)
Nervio Facial/anatomía & histología , Imagen por Resonancia Magnética , Tomografía Computarizada por Rayos X , Anatomía Transversal , Arterias/inervación , Cerebelo/irrigación sanguínea , Nervio de la Cuerda del Tímpano/anatomía & histología , Medios de Contraste , Osículos del Oído/inervación , Enfermedades del Nervio Facial/patología , Gadolinio , Humanos , Vías Nerviosas/anatomía & histología , Glándula Parótida/inervación , Hueso Petroso/inervación , Puente/anatomía & histologíaAsunto(s)
Conducción Ósea , Cóclea/fisiología , Osículos del Oído/fisiología , Contracción Muscular , Miofibrillas/fisiología , Membrana Timpánica/fisiología , Estimulación Acústica , Animales , Gatos , Nervio Coclear/fisiología , Osículos del Oído/inervación , Estimulación Eléctrica , Nervio Facial/fisiología , Neuronas Motoras/fisiología , Sonido , Tensor del Tímpano/inervación , Tensor del Tímpano/fisiología , Membrana Timpánica/inervaciónAsunto(s)
Osículos del Oído/inervación , Párpados , Parálisis Facial/diagnóstico , Adolescente , Adulto , Anciano , Audiometría , Niño , Femenino , Pérdida Auditiva Provocada por Ruido , Humanos , Masculino , Persona de Mediana Edad , RuidoRESUMEN
1. The muscle fibres of the tensor tympani and stapedius of the cat have been examined in the light microscope in teased preparations after cholinesterase staining and in the electron microscope.2. In both muscles, two kinds of fibre have been found: those with an individual end-plate and those with multiple nerve terminals.3. The stapedius fibres with an end-plate have fibrils regularly separated from each other by sarcoplasmic reticulum, a straight Z line, transverse tubular T system elements regularly occurring at the junction of A and I bands, an M line, an extensive sole plate area, and numerous post-junctional sarcolemmal infoldings under the nerve terminal. This type of muscle fibre in the tensor tympani has all of these features except that the fibrils are not well separated from each other, T system elements are absent in some sarcomeres, and a typical M line is absent.4. Compared to the individually innervated fibres, the fibres with multiple endings have fibrils poorly separated from each other by sarcoplasmic reticulum, a jagged Z line, very few T system elements, a less extensive sole plate area, and essentially no folds under the nerve terminal. These fibres in both muscles have M lines.5. Muscle fibres have thus been found in both the tensor tympani and stapedius of the cat which conform in their innervation, the structure of their motor nerve endings, and their internal structure to many of the morphological characteristics which are exhibited by slow muscle fibres elsewhere.