大鼠延髓网状背侧亚核下行投射终末在脊髓灰质的分布

本研究应用PHA－L顺行追踪技术研究了大风延髓网状背测亚核（SRD）至脊髓灰质下行投射的终止部位。结果表明：SRD发出的下行纤维走行于脊髓的背外侧京中，从高位至低位，脊髓灰质中的PHA－L顺标终末的密度逐渐降低。SRD的下行投射终未在脊髓中具有明显的同侧分布优势，主要终止在同侧脊历灰质的Ⅳ～Ⅶ层和X层，Ⅰ、Ⅱ层中只有少量的标记终末，对侧脊髓灰质中除了在Ⅳ层和X层中有中等密度的颁标终末分布外，其余各层中几乎无标记终未、PHA－L顺标终未与BSI-B4标记的初级传入C纤维终末在Ⅰ．Ⅱ层内重叠公布．本研究为SRD在调控脊髓的伤害性信息传递方面也起重要作用这一论点提供了直接的形态学依据．

DISTRIBUTIONS OF THE DESCENDING PROJECTION TERMINALS FROM THE SUBNUCLEUS RETICULARIS DORSALIS TO THE SPINAL GRAY MATTER IN THE RAT

The precise termination areas of the descending projection from the medullary subnucleus reticularis dorsalis (SRD) to spinal gray matter in the rat were investigated by injection of an anterograde tracer, phaseol us vulgaris leucoagglu tinin (PHA-L) into the SRD. The present results showed that PHA-L anterogradely labeled fibers originating from the SRD traveled through the dorsolateral funiculus and mainly terminated at the ipsilateral laminae Ⅳ ~ Ⅶ and X of the cervical and thoracic cords, In addition, PHA-L labeled fibers and terminals were also sparsely detected in laminae Ⅰ and Ⅱ, wherePHA-L labeled fibers and terminals overlapped with those labeled by Banderea Simplicdelia Isolectin-B4 (BSI-B4). In the other laininae of the spinal gray matter, there were almost no PHA-L laheled fibers and terminals. The present results provided direct morphological evidence that SRD might play an important role in modulation and control of the noxious informa tion transmission within the spinal cord.