Caballero-Bleda M, Witter M P
Department of Morphological Sciences, Faculty of Medicine, University of Murcia, Spain.
J Comp Neurol. 1993 Feb 1;328(1):115-29. doi: 10.1002/cne.903280109.
The regional and laminar organization of the projections from the presubiculum and the parasubiculum to the entorhinal cortex was analyzed in the rat with the anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHA-L). The projections from the presubiculum were bilateral and confined to layers III and I of the medial entorhinal area (MEA). Both the ispi- and the contralateral projections showed similar distributions and were almost of equal density. Projections to layer III of the entorhinal cortex arose predominantly from superficial layers of the presubiculum, whereas the fibers that reach layer I of the entorhinal cortex appear to originate preferentially from the deep layers of the presubiculum. These fibers also appeared to innervate weakly layer II of MEA. The parasubiculum distributed projections not only to MEA but also to the lateral entorhinal area (LEA), innervating layer II selectively. The innervation of LEA was quite dense and extensive. Very weak projections from the parasubiculum to the contralateral entorhinal cortex were observed in this study. The position of the terminal plexus in the entorhinal cortex was determined by the point of origin along both the dorsoventral and transverse or proximodistal axes of the presubiculum and parasubiculum. Projections from the presubiculum and parasubiculum entered the entorhinal cortex at the level of the injection, or slightly ventral to it, and the main terminal field was always present ventrally to the injection site. The dorsoventral axis of origin thus corresponded to a similarly oriented axis of termination in the entorhinal cortex. The distribution in relation to the origin along the transverse axis was more complex, and differences between the presubiculum and parasubiculum were present. The proximal presubiculum, i.e., the part closest to the subiculum, projected to the most lateral part of MEA and the central part of the presubiculum sent fibers to the most medial part of MEA. The distal part of the presubiculum, i.e., the part that borders the parasubiculum, projected to the central part of MEA. Projections from the portion of the parasubiculum directly adjacent to the presubiculum, the so-called proximal parasubiculum, reached medial parts of MEA, and those originating in the central part distributed preferentially to lateral parts of MEA and adjacent medial parts of LEA. The distal part of the parasubiculum that borders the entorhinal cortex projected mainly to almost the full mediolateral extent of LEA.(ABSTRACT TRUNCATED AT 400 WORDS)
运用顺行示踪剂菜豆白细胞凝集素（PHA-L），在大鼠中分析了前下托和旁下托向内嗅皮质投射的区域及分层组织。前下托的投射是双侧性的，局限于内侧内嗅区（MEA）的III层和I层。同侧和对侧投射均呈现相似的分布，且密度几乎相等。向内嗅皮质III层的投射主要起源于前下托的浅层，而到达内嗅皮质I层的纤维似乎优先起源于前下托的深层。这些纤维对内嗅区II层的支配也较弱。旁下托不仅向内侧内嗅区投射，还向外侧内嗅区（LEA）投射，且选择性地支配II层。对外侧内嗅区的支配相当密集且广泛。在本研究中观察到旁下托向对侧内嗅皮质的投射非常微弱。内嗅皮质中终末丛的位置由前下托和旁下托在背腹侧以及横向或近远侧轴上的起源点决定。前下托和旁下托的投射在注射水平或其稍下方进入内嗅皮质，主要终末场总是位于注射部位的腹侧。因此，起源的背腹侧轴与内嗅皮质中类似定向的终末轴相对应。沿横轴的起源分布更为复杂，前下托和旁下托之间存在差异。前下托近端，即最靠近下托的部分，投射到内侧内嗅区的最外侧部分，前下托中部将纤维发送到内侧内嗅区的最内侧部分。前下托远端，即与旁下托相邻的部分，投射到内侧内嗅区的中部。与前下托直接相邻的旁下托部分，即所谓的近端旁下托，其投射到达内侧内嗅区的内侧部分，起源于中部的投射优先分布到内侧内嗅区的外侧部分和外侧内嗅区相邻的内侧部分。与内嗅皮质相邻的旁下托远端主要投射到外侧内嗅区几乎整个内外侧范围。（摘要截取自400字）
