Henry M A, Westrum L E
Department of Neurological Surgery, School of Medicine, University of Washington, Seattle 98195.
Somatosens Mot Res. 1990;7(4):447-62. doi: 10.3109/08990229009144719.
Horseradish peroxidase (HRP) was injected into either a single maxillary or a single mandibular primary (deciduous) cuspid tooth of 8- to 10-week-old kittens. The large apex of the primary cuspid allowed for some leakage of the HRP from the pulpal chamber to the periodontal ligament (PDL). Thus, the injection procedure resulted in the application of HRP to the PDL as well as to the pulpal tissues. The transganglionic transport of HRP resulted in discrete terminal fields within the spinal trigeminal nucleus (STN) and the main sensory nucleus (MSN). These projections were clearly somatotopically organized within the STN, but less so within MSN. Within pars oralis (PO) and pars interpolaris (PI), mandibular cuspid dental structures (MdCDS) were represented in a dorsal position relative to the maxillary cuspid dental structures (MxCDS), whereas within pars caudalis (PC) and the adjacent reticular formation the somatotopic representation was not dorsoventral, but rather mediolateral, with the MdCDS represented more medially than the MxCDS. Areas of overlap between MxCDS and MdCDS were found within MSN and to a lesser degree within the superficial laminae of PC. In addition, the fiber pathway leading to labeled somata in the mesencephalic trigeminal (Mes V) nucleus was clearly identified. The majority of the fibers traced to the Mes V nucleus exited the spinal trigeminal tract at the level of the transition from PO to the MSN and traversed the nuclear region in a position dorsal to and separate from the trigeminal motor tract. As in STN, fibers within the caudal Mes V tract appeared to be somatotopically organized, with the fibers from the MdCDS generally more dorsal than the ones from the MxCDS. Labeled fibers, some with terminal arbors, were also identified in close association with the trigeminal motor tract. The findings show a complex pattern of central representation in the immature feline central nervous system for deciduous dental structures.
将辣根过氧化物酶（HRP）注射到8至10周龄小猫的单个上颌或单个下颌乳尖牙中。乳尖牙的大根尖使得HRP从牙髓腔渗漏到牙周膜（PDL）。因此，注射过程导致HRP应用于PDL以及牙髓组织。HRP的跨神经节运输导致在三叉神经脊束核（STN）和主感觉核（MSN）内出现离散的终末场。这些投射在STN内明显按躯体定位组织，但在MSN内则不太明显。在口部（PO）和极间部（PI）内，下颌尖牙牙结构（MdCDS）相对于上颌尖牙牙结构（MxCDS）呈背侧代表，而在尾部（PC）和相邻网状结构内，躯体定位代表不是背腹向的，而是中外侧的，MdCDS比MxCDS更靠内侧代表。在MSN内以及在PC浅层层内程度较轻地发现了MxCDS和MdCDS之间的重叠区域。此外，清楚地识别了通向中脑三叉神经（Mes V）核中标记胞体的纤维通路。追踪到Mes V核的大多数纤维在从PO到MSN的过渡水平离开三叉神经脊束，并在与三叉神经运动束背侧且分开的位置穿过核区域。与STN一样，尾侧Mes V束内的纤维似乎按躯体定位组织，来自MdCDS的纤维通常比来自MxCDS的纤维更靠背侧。还发现标记纤维，其中一些带有终末分支，与三叉神经运动束紧密相关。这些发现显示了未成熟猫中枢神经系统中乳牙结构的复杂中枢代表模式。
