Field P M, Seeley P J, Frotscher M, Raisman G
Norman and Sadie Lee Research Centre, National Institute for Medical Research, London, U.K.
Neuroscience. 1991;41(2-3):713-27. doi: 10.1016/0306-4522(91)90362-r.
Fragments containing different cytoarchitectonic fields were dissected out of late embryonic rat hippocampal primordia and transplanted into the hippocampus or septum of adult syngeneic hosts. Field CA3 transplants contained clusters of large, angular (pyramidal) cell bodies surrounded by a radiating corona of dendrites. These cells stained selectively with our monoclonal antibody Py, and a proportion were labelled by [3H]thymidine administered on the 15th day of embryonic life. Field CA1 transplants contained smaller, angular, Py-negative cells, which formed elongated laminae rather than globular clusters. The ability of the host dentate granule cells to project to the transplants was examined by (1) the Timm stain for mossy fibres, (2) electron microscopy of Golgi-impregnated CA3 pyramidal neurons in the transplants, and (3) quantitative electron microscopic assessment of the proportions of large mossy fibre terminals in the synaptic population of the transplants. The Timm stain showed that CA3 transplants received a projection from host dentate granule cells when the transplants were placed in direct contact with the axons in the host mossy fibre pathway. As in the normal host field CA3, the ingrowing mossy fibres terminated selectively on the juxtacellular regions of the dendritic tree and ignored the major part of the dendrites in the radiating corona. The electron micrographs showed that within this territory the host mossy fibres formed synaptic terminals with all the complex features typical of normal mossy fibres, and were presynaptic to complex spines arising from the juxtacellular region of Golgi-impregnated donor CA3 pyramidal cells. The quantitative electron microscopic study demonstrated that the mossy fibre-innervated juxtacellular regions of the field CA3 transplants had up to 20% of the normal density of mossy fibre synapses found in the stratum lucidum of field CA3 in situ. CA3 transplants which were placed in the septum, remote from the host mossy fibres, had either trivial numbers of mossy fibre synapses or none. This confirmed that the abundant mossy fibre terminals in the intrahippocampal CA3 transplants were of host origin, and not due to donor dentate granule cells inadvertently included in the grafts. The selectivity of the host dentate projection for field CA3 transplants was demonstrated by the observation that CA1 transplants in the same locations received only slight mossy fibre projections in the Timm stain, and in electron micrographs their synaptic population had only insignificant numbers of large mossy fibre terminals.(ABSTRACT TRUNCATED AT 400 WORDS)
从晚期胚胎大鼠海马原基中分离出包含不同细胞构筑区域的片段，移植到同基因成年宿主的海马或隔区。CA3区移植组织包含成簇的大型、角形（锥体）细胞体，周围有放射状的树突冠。这些细胞用我们的单克隆抗体Py进行选择性染色，一部分细胞在胚胎期第15天注射[3H]胸腺嘧啶核苷后被标记。CA1区移植组织包含较小的、角形的、Py阴性细胞，这些细胞形成细长的薄片而不是球状簇。通过以下方法检测宿主齿状颗粒细胞向移植组织投射的能力：（1）用Timm染色法检测苔藓纤维；（2）对移植组织中经高尔基染色的CA3锥体神经元进行电子显微镜观察；（3）对移植组织突触群中大型苔藓纤维终末的比例进行定量电子显微镜评估。Timm染色显示，当CA3区移植组织与宿主苔藓纤维通路中的轴突直接接触时，会接受来自宿主齿状颗粒细胞的投射。与正常宿主的CA3区一样，长入的苔藓纤维选择性地终止于树突树的近细胞区域，而忽略了放射状冠中的大部分树突。电子显微镜照片显示，在这个区域内，宿主苔藓纤维形成了具有正常苔藓纤维典型所有复杂特征的突触终末，并且是来自经高尔基染色的供体CA3锥体细胞近细胞区域产生的复杂棘突的突触前成分。定量电子显微镜研究表明，CA3区移植组织中苔藓纤维支配的近细胞区域的苔藓纤维突触密度高达原位CA3区透明层中正常苔藓纤维突触密度的20%。置于隔区、远离宿主苔藓纤维的CA3区移植组织，苔藓纤维突触数量极少或没有。这证实了海马内CA3区移植组织中丰富的苔藓纤维终末起源于宿主，而不是由于移植组织中意外包含的供体齿状颗粒细胞。在相同位置的CA1区移植组织在Timm染色中仅接受轻微的苔藓纤维投射，并且在电子显微镜照片中其突触群中大型苔藓纤维终末数量极少，这一观察结果证明了宿主齿状投射对CA3区移植组织的选择性。（摘要截断于400字）
