Craig A D, Linington A J, Kniffki K D
Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona 85013.
J Comp Neurol. 1989 Nov 22;289(4):568-85. doi: 10.1002/cne.902890404.
The double fluorescent retrograde labeling method was used to examine the distribution of spinothalamic tract (STT) cells that project to the medial and lateral thalamus in the cat. Injections of one fluorescent tracer (Fast Blue or Diamidino Yellow) were made throughout the lateral thalamus and injections of the other tracer were made in the medial thalamus at sites extrapolated from recording track coordinates. Survival times were successively extended (up to 5 weeks) in order to maximize labeling in both the cervical and lumbosacral spinal cord. On average, over 2,000 labeled contralateral STT cells were counted in serial sections from segments C5-7 and L5-S2. Numerical variability of the order of a factor of two was attributable to inherent differences between individual animals. The total number of cells labeled with fluorescent tracers was comparable to the number labeled with horseradish peroxidase in control cases, although there were significant differences between the laminar distributions of labeling produced by the two methods. Injections made anterior to the thalamus to control for labeling due to leakage or passing fibers did not produce substantial spinal labeling. The laminar distribution of fluorescent dye-labeled STT cells was consistent; about half (47%) were located in lamina I, 8% were in lamina V, 5% in lamina VI, 20% in lamina VII, and 20% in lamina VIII. The proportions of STT cells in laminae I and V were higher in cervical segments (57% and 12%, respectively) than in lumbosacral segments (38% and 6%). The dominant contribution of lamina I cells to the STT thus revealed by the fluorescent tracers is striking. The proportions of STT cells labeled from the medial and the lateral thalamus varied with segmental and laminar location and with injection placement. The majority (62%) of STT cells in most cases projected only to the medial thalamus, 25% projected only to the lateral thalamus, and 13% projected to both. The STT cell populations in laminae I, VII, and VIII each displayed this common projection pattern. In contrast, cells in laminae V and VI projected predominantly to the lateral thalamus. Twice as many STT cells in lamina I (19%) projected to both the medial and the lateral thalamus as from other laminae. A greater proportion of laminae V-VIII STT cells in segments L5-6 projected to the lateral thalamus, and in S1-2, more projected to the medial thalamus.(ABSTRACT TRUNCATED AT 400 WORDS)
采用双荧光逆行标记法研究猫脊髓丘脑束（STT）细胞向内侧和外侧丘脑投射的分布情况。在整个外侧丘脑注射一种荧光示踪剂（快蓝或双脒基黄），并在根据记录轨迹坐标外推的内侧丘脑部位注射另一种示踪剂。依次延长存活时间（最长至5周），以最大限度地标记颈段和腰骶段脊髓。平均而言，在C5 - 7节段和L5 - S2节段的连续切片中，对超过2000个标记的对侧STT细胞进行了计数。数量上两倍左右的变化归因于个体动物之间的固有差异。荧光示踪剂标记的细胞总数与对照病例中辣根过氧化物酶标记的细胞数相当，尽管两种方法产生的标记在层状分布上存在显著差异。在丘脑前方进行注射以控制因渗漏或纤维通过导致的标记，未产生大量脊髓标记。荧光染料标记的STT细胞的层状分布是一致的；约一半（47%）位于I层，8%位于V层，5%位于VI层, 20%位于VII层，20%位于VIII层。I层和V层中STT细胞的比例在颈段（分别为57%和12%）高于腰骶段（分别为38%和6%）。荧光示踪剂揭示的I层细胞对STT的主要贡献非常显著。从内侧和外侧丘脑标记的STT细胞比例随节段和层状位置以及注射部位而变化。在大多数情况下，大多数（62%）STT细胞仅投射到内侧丘脑，25%仅投射到外侧丘脑，13%投射到两者。I层、VII层和VIII层中的STT细胞群体均呈现这种常见的投射模式。相比之下，V层和VI层中的细胞主要投射到外侧丘脑。I层中投射到内侧和外侧丘脑的STT细胞数量是其他层的两倍（19%）。L5 - 6节段中V - VIII层的STT细胞投射到外侧丘脑的比例更高，而在S1 - 2节段，投射到内侧丘脑的更多。（摘要截断于400字）
