Thermosensitivity and its possible fine-structural basis in mechanoreceptors in the beak skin of geese

摘要: An electrophysiological study on single afferent nerve fibers in the ophthalmic of goose revealed two kinds temperature-sensitive mechanoreceptors beak, which are innervated by large-diameter myelinated axons. Some Herbst corpuscles, display rapidly adapting responses to mechanical stimulation, discharge tonically cooling receptive field. A static response maximum occurs at temperatures between 15 and 25°C. The vibration sensitivity corpuscles decreases with temperature. Many slowly Ruffini endings also respond sustained discharges but behave like warming temperature maximal different units varies 10 30°C. The fine structure was investigated electron microscopically order elucidate possible morphological substrates for specific functional properties receptor types. Both characterized a distinct combination nervous nonnervous (auxiliary) tissue elements occurrence special structural sensory endings. Such “transducer sites” presumably correspond those areas membrane where mechanoelectric transduction process takes place. most prominent constituent transducer site is spurlike axon process, corpuscle projects lamellae inner core, comes into contact collagenous microfibrils, either directly or indirectly through mediation Schwann cell processes. Two variants were recognized found occur locations dermis underlying horny covering bill tip. One type distinguished presence specialized terminal making initial branches arborizing axon. other ending lacks cell. The structure-function relations discussed basis ultrastructural observations. It argued that characteristics both types stimuli result from kind arrangements auxiliary structures latter. On this thermosensitivity can be explained as consequence differential effects changes have one hand auxillary mechanically elicited potential. concluded some may secondary differentiation makes discriminative function and, therefore, does not necessarily conflict principle modality specificity receptors.