Functional conversion from sucking to mastication : An immunoelectron microscopic study concerning the development of peripheral nervous system.

哺乳动物在出生后的发育过程中经历了从吸吮到咀嚼的功能转换。这种功能的转换似乎与周围神经系统的发育和成熟密切相关，特别是在牙周膜的神经支配中。在这项研究中，出生后的发展Ruffini结束，分类低阈值拉伸机械感受器，超微结构研究在上切牙的大鼠通过蛋白基因产物9.5（PGP 9.5）免疫组化。Wistar大鼠按出生后天数分为6组：1、4天（切牙未萌出期）、7-11天（切牙萌出期）、15天（上下切牙咬合开始期）、25天（上下第一磨牙咬合开始期）和80天（功能咬合期）。(1)值得注意的是，在4d时，机械感受器样结构被两个或多个许旺鞘包围 ...更多信息 出生后(2)在切牙萌出阶段，部分轴突终末穿过雪旺鞘的缝隙，形成指状突起，称为轴突棘。这些轴突棘的数量和长度，以及在从切牙萌出的时期，咬合建立分支发展。(3)在切牙咬合开始阶段，轴突终末内各种类型的小泡数量减少。(4)轴突终末中的线粒体数量随时间的推移而增加，并在上下切牙咬合开始后变得更长。(5)轴突棘不与胶原纤维接触，表明无定形层的介入。无定形层增厚和分层后，发病之间的门齿咬合。总之，本研究揭示了Ruffini末梢的超微结构分化和成熟的急剧进行从切牙萌出到咬合建立的时期。少

Mammals go through functional conversion from sucking to mastication during their postnatal development. This functional conversion seems to be closely related to the development and maturation of the peripheral nervous system, particularly in the innervation of the periodontal ligament. In this study, the postnatal development of Ruffini endings, categorized by low-threshold stretch mechanoreceptors, was ultrastructurally investigated in the upper incisors of the rat by means of protein gene product 9.5 (PGP 9.5) immunohistochemistry. The Wistar rats were divided into six groups according to their postnatal days : 1,4 (incisor un-erupted stage), 7-11 (incisor eruption stage), 15 (commencement stage of occlusion between upper and lower incisors), 25 (commencement stage of occlusion between upper and lower first molars), and 80 days (functional occlusion stage).(1) It is notable that mechanoreceptor-like structures being surrounded by two or more Schwann sheaths were recognized at 4days … More after birth. (2) At incisor eruption stage, parts of the axon terminals extended through the slits of Schwann sheaths and formed finger-like projections called axonal spines. These axonal spines developed in number and in length as well as in ramification during the period from incisor eruption to that of occlusal establishment. (3) Various types of small vesicles in axon terminals have decreased in number after the commencement stage of incisor occlusion. (4) The mitochondria in the axon terminals increased in number with time and became longer after the onset of occlusion between the upper and lower incisors. (5) The axonal spines makes no contact with collagen filament, indicating the intervention of an amorphous layr. The amorphous layr thickened and lamellated after the onset of occlusion between incisors. In conclusion, present study has disclosed that the ultrastructural differentiation and maturation of Ruffini endings proceed drastically during the period from incisor eruption to that of occlusal establishment. Less