Light And Electron Microscopy Of The Trigeminal Nerve To The Solitary Tract Nucleus

Nucleus tractus solitarii (NTS) and trigeminal nerve (TGN) were classically considered as the visceral afferent relay nucleus and the general somatic sensory nerve respectively. To clarify the afferent projecting pathway from somatic TGN to NTS and the relationship between the primary afferent projections of TGN and the visceral nerves in NTS might provide the morphological data for explaning the mechanism of acupuncture analgesia in the field of TGN.Although there were a few reports concerning the projections from TGN to NTS, due to the methodologic limitation, the question of which branches of TGN project to NTS was unclear. The reports of relationship between the projecting fibers and terminals of TGN and the visceral nerves were even not found until now. By using the techniques of light microscopy and electron microscopy, localization combined with qualifica-tion,and gradual deepening the investigation, the problems mentioned ab(?)ve were systematically studied.In the present study,some significant results were obtained and the following two points of them were more prominent.1. Analysis of our experimental results and reported data indicated that only lingual, inferior alveolar and sphenopalatine nerves of TGN projected to NTS. The terminals of these three nerves were distributed in respective specific areas, the distribution area of the lingual nerve was the largest and that of the inferior alveolar nerve the smallest, Under the light microscope, the projecting area from TGN and the visceral nerves (VII, XI, X) were overlapping, and the overlapping areas of lingual nerve and glossopharyngeal, vagus nerves were especially evident. Under the electron microscope, the lingual nerve was taken as the model of observation. The terminal patterns and types of synapses of the lingual nerve were similar to that of the visceral nerves (IX, X), and significant convergence was not found...