Adelmann G, Deller T, Frotscher M
Institute of Anatomy, University of Freiburg, Germany.
Anat Embryol (Berl). 1996 May;193(5):481-93. doi: 10.1007/BF00185879.
The fimbria is a major route for afferent and efferent fibers of the hippocampal formation. However, little is known about the intrinsic organization of the fimbria-fornix complex. In this study, the anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHAL) was used to analyze the ultrastructure and topography of identified fiber tracts within the fimbria-fornix. Septo-hippocampal fibers are loosely distributed throughout the fimbria-fornix. Commissural fibers cross the midline in the ventral hippocampal commissure and form a tight fiber bundle in the fimbria. Crossed entorhino-hippocampal fibers cross the midline in the ventral hippocampal commissure rostral to the commissural fiber bundle, and crossed entorhino-entorhinal fibers pass through the dorsal hippocampal commissure. This suggests a topographical organization of fiber tracts within the fimbria-fornix that reflects the laminar organization of the hippocampal target structure: fibers of the diffusely terminating septohippocampal projection are loosely distributed throughout the fimbria-fornix, while those projections that are known to terminate in specific laminae of the hippocampal formation (commissural projection, crossed entorhino-hippocampal projection) form fiber bundles within the fimbria and the ventral hippocampal commissure.
伞是海马结构传入和传出纤维的主要路径。然而，关于伞 - 穹窿复合体的内在组织结构却知之甚少。在本研究中，使用顺行示踪剂菜豆白细胞凝集素（PHAL）来分析伞 - 穹窿内已识别纤维束的超微结构和拓扑结构。隔 - 海马纤维松散地分布于整个伞 - 穹窿。连合纤维在腹侧海马连合处穿过中线，并在伞中形成紧密的纤维束。交叉的内嗅 - 海马纤维在连合纤维束前方的腹侧海马连合处穿过中线，而交叉的内嗅 - 内嗅纤维则穿过背侧海马连合。这表明伞 - 穹窿内纤维束的拓扑组织反映了海马靶结构的分层组织：弥散终止的隔海马投射的纤维松散地分布于整个伞 - 穹窿，而那些已知终止于海马结构特定层的投射（连合投射、交叉的内嗅 - 海马投射）则在伞和腹侧海马连合内形成纤维束。
