Voigt T, LeVay S, Stamnes M A
Vision Center Laboratory, Salk Institute for Biological Studies, San Diego, CA 92138-9216.
J Comp Neurol. 1988 Jun 15;272(3):450-60. doi: 10.1002/cne.902720312.
The connections between the left and right 17-18 border regions of the cat's visual cortex were labeled by axonal transport of peroxidase-conjugated wheat-germ agglutinin (WGA-HRP) and examined by light and electron microscopy. The cells of origin of the pathway were further characterized by transport of fluorescent microspheres ("beads") followed by in vitro injection of cells with Lucifer Yellow, and by beads transport followed by immunocytochemistry with antibodies to gamma-aminobutyric acid (GABA). The cells of origin of the callosal pathway were located in the lower part of layer 2/3, the upper part of layer 4, and layer 6. In layers 2/3 and 6, they were pyramidal cells; in layer 4 they were star pyramids or spiny stellate cells. None of them were spinefree or sparsely spinous cells, and none were GABA-positive. The axon terminals of the callosal pathway formed type 1 (asymmetric) synapses, and most of them contacted dendritic spines. Both the cells of origin and the terminals were arranged in patches. The findings suggest that the direct action of the callosal pathway is excitatory. The callosal system appears to represent only a subset of the cell types that have intrinsic horizontal projections within areas 17 or 18.
通过过氧化物酶结合的麦胚凝集素（WGA-HRP）的轴突运输对猫视觉皮层左右17-18边界区域之间的连接进行标记，并通过光学显微镜和电子显微镜进行检查。通过荧光微球（“珠子”）运输，随后对细胞进行体外注射鲁米诺黄，以及通过珠子运输随后用抗γ-氨基丁酸（GABA）抗体进行免疫细胞化学，进一步表征该通路的起源细胞。胼胝体通路的起源细胞位于第2/3层下部、第4层上部和第6层。在第2/3层和第6层，它们是锥体细胞；在第4层，它们是星形锥体或棘状星形细胞。它们中没有无棘或棘少的细胞，也没有GABA阳性细胞。胼胝体通路的轴突终末形成1型（不对称）突触，且大多数与树突棘接触。起源细胞和终末均呈斑块状排列。这些发现表明胼胝体通路的直接作用是兴奋性的。胼胝体系统似乎仅代表在17区或18区内具有内在水平投射的细胞类型的一个子集。
