Relationships between the terminal arborizations of hair follicle afferent fibres and dendritic trees of spinocervical tract (s.c.t.) neurones were studied using intra-axonal and intracellular injections of horseradish peroxidase in chloralose-anaesthetized, paralysed cats. 2. Seventeen afferent-neurone pairs were successfully stained and their receptive fields determined. Ten of the pairs had s.c.t. neurones with a field containing that of the hair follicle afferent and seven pairs had separate fields on the hind limb. 3. Where the afferent fibre's field was outside the neurone's field there were no indications of synaptic contacts between the two neuronal elements. 4. Synaptic contacts were always observed (at the light microscope level) for the ten pairs with the hair afferent's receptive field contained within the s.c.t. cell's field. Contacts were always made by the branches of only a single collateral from the hair follicle afferent fibre. The numbers and locations of synaptic contacts were related to the relative positions of the receptive field: where the hair follicle afferent's field was centrally placed there were many (forty to sixty) contacts on proximal dendrites; where the hair follicle afferent's field was peripherally placed in the s.c.t. cell's receptive field there were few contacts (two to thirteen) and these were peripherally placed on the dendritic tree. Where the primary afferent fibre had a centrally placed field contacts upon dendritic spines were observed. 5. The results are discussed in terms of the synthesis of receptive fields and the organization of neuronal connexions within the mammalian spinal cord.
摘要
利用辣根过氧化物酶的轴突内和细胞内注射技术，在水合氯醛麻醉、麻痹的猫身上研究了毛囊传入纤维的终末分支与脊髓颈段神经元树突之间的关系。2. 成功染色了17对传入神经元，并确定了它们的感受野。其中10对脊髓颈段神经元的感受野包含毛囊传入神经元的感受野，7对在 hind limb 上有独立的感受野。3. 当传入纤维的感受野在神经元感受野之外时，没有迹象表明这两个神经元成分之间存在突触联系。4. 在脊髓颈段细胞感受野内包含毛囊传入神经元感受野的10对神经元中（在光学显微镜水平）总是能观察到突触联系。这些联系总是由毛囊传入纤维的单个侧支的分支形成。突触联系的数量和位置与感受野的相对位置有关：当毛囊传入神经元的感受野位于中央时，近端树突上有许多（40至60个）联系；当毛囊传入神经元的感受野位于脊髓颈段细胞感受野的外周时，联系很少（2至13个），且这些联系位于树突树的外周。当初级传入纤维的感受野位于中央时，可观察到树突棘上的联系。5. 根据感受野的合成以及哺乳动物脊髓内神经元连接的组织来讨论这些结果。
