Tsuru K, Otani K, Kajiyama K, Suemune S, Shigenaga Y
Department of Oral Anatomy (1st Division), Hiroshima University School of Dentistry, Japan.
Brain Res. 1989 Apr 17;485(1):29-61. doi: 10.1016/0006-8993(89)90665-3.
Intra-axonal recording and horseradish peroxidase (HRP) injection techniques were employed to define the response properties of low-threshold mechanoreceptive periodontal afferents and of the tooth pulp afferents and the morphological characteristics of their axon arbors in the nucleus principalis (Vp) and rostrodorsomedial (Vo.r) and dorsomedial parts (Vo.dm) of the nucleus oralis (Vo). The central terminals of 3 fast adapting (FA) and 4 slowly adapting (SA) periodontal afferents and 4 tooth pulp (TP) afferents were recovered for detailed analyses. Stained axons in the trigeminal sensory tract ascended and descended (bifurcating fibers), or descended without bifurcation (descending non-bifurcating fibers). The ratio of the bifurcating fibers to the descending non-bifurcating fibers was about three to one for each type of afferents. The main collaterals given off from the ascending branches terminated in the Vp. Most collaterals given off from the descending branches terminated in the Vo with the exception of few instances. In case of the FA afferents, the ascending branches gave off all main collaterals into the Vp with rostrocaudal and dorsoventral continuities in their arbors, whereas the descending branches gave off all main collaterals, except two collaterals, into the Vo with rostrocaudal discontinuities. The projections from the FA afferents to the Vo.dm was predominant in terms of the number of boutons and the length of preterminal and terminal branches. In case of the SA afferents, the collaterals from the ascending and descending branches formed rostrocaudally and dorsoventrally discontinuous terminal arbors. In terms of the density of boutons the SA afferents were divided into two subtypes. One had a preferential projection into the Vp or Vo, whereas others lacked a selective projection. In case of the TP afferents, the main collaterals of the ascending branches formed partially overlapping terminal arbors, but the terminal arbors formed by the collateral of the descending branches did not overlap. The frequency of collaterals of the TP afferents was less than that of the other types of afferents. The terminal arbors including the density of boutons of the pulpal afferents were less extensive than those of the other types of afferents. The average size of varicosities became smaller in the following subdivisions. Vp, Vo.r and Vo.dm for SA and TP afferents. The size of varicosities of the TP afferents was smaller and that of the FA afferents was larger than that of the SA afferents.(ABSTRACT TRUNCATED AT 400 WORDS)
采用轴突内记录和辣根过氧化物酶（HRP）注射技术，来确定低阈值机械感受性牙周传入纤维和牙髓传入纤维的反应特性，以及它们在口腔核（Vo）的主核（Vp）、吻背内侧（Vo.r）和背内侧部分（Vo.dm）的轴突分支的形态特征。回收了3条快速适应（FA）和4条缓慢适应（SA）牙周传入纤维以及4条牙髓（TP）传入纤维的中枢终末进行详细分析。三叉神经感觉束中染色的轴突有上升和下降的（分支纤维），或下降但无分支的（下行无分支纤维）。每种传入纤维类型的分支纤维与下行无分支纤维的比例约为三比一。上升分支发出的主要侧支终止于Vp。除少数情况外，下行分支发出的大多数侧支终止于Vo。对于FA传入纤维，上升分支将所有主要侧支发放到Vp，其分支在前后和背腹方向上连续，而下行分支将除两条侧支外的所有主要侧支发放到Vo，其分支在前后方向上不连续。就终扣数量以及终末前和终末分支的长度而言，FA传入纤维向Vo.dm的投射占主导。对于SA传入纤维，上升和下行分支的侧支形成前后和背腹方向上不连续的终末分支。就终扣密度而言，SA传入纤维分为两个亚型。一个亚型优先投射到Vp或Vo，而其他亚型则缺乏选择性投射。对于TP传入纤维，上升分支的主要侧支形成部分重叠的终末分支，但下行分支的侧支形成的终末分支不重叠。TP传入纤维的侧支频率低于其他类型的传入纤维。牙髓传入纤维的终末分支，包括终扣密度，比其他类型的传入纤维范围更小。在以下亚区，曲张体的平均大小变小。SA和TP传入纤维的Vp、Vo.r和Vo.dm。TP传入纤维的曲张体大小比SA传入纤维小，FA传入纤维的曲张体大小比SA传入纤维大。（摘要截于400字）
