ラット茸状乳頭の形態分化ならびに形態維持におよぼす脱神経の影響
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概要
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To elucidate the trophic function of chorda tympani-lingual nerve during postnatal differentiation of rat fungiform papilla, unilateral neurectomy, nerve transection or nerve crush (axonotmesis) were performed at day 1 and at weeks 1,2,3,4 and 7 after birth. For the experiment involving neurectomy, specimens of tongue were obtained at days 7 and 10,weeks 2,3,4,6,and 8,and months 3 and 4 after denervation. For the experiment involving nerve transection or nerve crush, specimens were obtained at weeks 4,6,and 8,and months 3,4,6,and 8 after denervation. The specimens were observed under the scanning electron microscope to examine the morphological changes of the denervated fungiform papillae. At first, neurectomized fungiform papillae were atrophic, then progressed to forms resemblings filiform papillae (filiform-like papillae). When an immature fungiform papilla was neurectomized, it eventually changed to a papilla identical to normal filiform papilla (quasi-filiform papilla). The elicited changes differed according to the time of neurectomy : it was found that early neurectomy resulted in more rapid and marked morphological changes of the fungiform papillae. Nerve-transected or nerve-crushed fungiform papillae degenerated after denervation, then the papillae began to redifferentiate to normal fungiform papillae 6 or 8 weeks after denervation. However, if the immature papillae were denervated by nerve transection, the papillae changed to quasi-filiform papillae and could not redifferentiate to normal fungiform papillae. On the other hand, when immature papillae were denervated by nerve crush, some denervated papillae could redifferentiate to normal fungiform papillae whereas others could not. These findings suggest : (1) Morphogenesis and structural maintenance of the fungiform papillae require the presence of the chorda tympani and/or lingual nerve. (2) Filiform-like papillae possess the ability to redifferentiate. (3) There are two kinds of quasi-filiform papillae ; one of them retains redifferentiation ability, the other loses this ability. (4) The ability to redifferentiate is determined by time of denervation and regeneration speed of the axon. (5) Fungiform papillae may be transformed filiform papillae induced and maintained by a neurotrophic factor or factors coming from the chorda tympani and/or lingual nerve.
- 福岡歯科大学学会の論文
- 1997-06-30