树内侧隔核/斜角带核垂直部—海马投射:菜豆白细胞凝集素顺行法研究

PROJECTIONS FROM THE MEDIAL SEPTAL NUCLEUS AND THE VERTICAL DIVISION OF DIAGONAL BAND NUCLEI TO THE HIPPOCAMPUS IN THE TREE SHREW-A PHASEOLUS VULGARIS LEUCOAGGLUTININ ANTEROGRADE TRACING STUDY

本研究用 PHA-L顺行追踪法观察了树鼠句内侧隔核 /斜角带核垂直部到海马的投射。结果表明 :( 1)海马内 PHA-L标记纤维根据形态特点可分为两种类型 : 型纤维较粗 ,分支多 ,有形态较大、数量较少的终末终扣 ; 型纤维纤细 ,分支少 ,有较多、较小的通过型终扣 ( boutons en passant)。 ( 2 )内侧隔核 /斜角带核垂直部到海马的投射存在着以下体部定位关系 :一侧向双侧海马均有投射 ,以同侧投射明显占优势 ;内侧隔核吻侧部主要投射到背侧海马和腹侧海马后部 ,内侧隔核尾侧部主要投射到腹侧海马前部 ;背侧海马齿状回内的投射纤维几乎都来自内侧隔核。 ( 3 )根据注射部位的不同 , 、 型纤维在背侧海马的分布有差异 ,其中内侧隔核吻侧部到背侧海马的纤维几乎均为 型纤维 ,而斜角带核垂直部到背侧海马的纤维既有 型纤维又有 型纤维。( 4 )背侧海马和腹侧海马内 型纤维的终扣结构极有可能与锥体细胞和颗粒细胞构成突触。本研究结果为进一步认识内侧隔核 /斜角带核垂直部 -海马通路提供了新的形态学依据。

The projection patterns of the medial septal nucleus (MS) and nucleus of diagonal band,vertical division (NDBV) to the hippocampal formation in the tree shrew (Tupaia belangeri chinensis) were investigated by means of anterograde axonal transport of Phaseolus vulgaris leucoagglutinin (PHA-L). (1) The PHA-L labeled projecting fibers in the hippocampus could be divided into two distinct fiber systems according to their shape. Type Ⅰfibers were thick and coarse axons carrying fewer but larger terminal boutons. Delicate thin type Ⅱfibers provided numerous passant varicosities. (2) The labeled efferents showed remarkable differences in topographic distribution in the hippocampus of tree shrew depending on the position of the injection site in MS/NDBV. The projections to hippocampus arising from one side of MS/NDBV showed ipsilateral predominance. The rostral part of MS (MSr) mainly projected to the dorsal hippocampus and the posterior division of ventral hippocampus. The projections to the anterior part of the ventral hippocampus rose nearly from the caudal part of MS (MSc). The afferents to dentate gyrus of the dorsal hippocampus almost came from MS. (3) TypeⅠ,Ⅱfibers were distributed differently in the dorsal hippocampus as the injection site was changed. The projecting fibers from MS were virtually typeⅠfibers, while the labeled projection fibers from NDBV contained typeⅠand typeⅡfibers. (4) TypeⅠ fibers usually infiltrated the stratum pyramidale and the stratum granulosum in the dorsal and ventral hippocampus, suggesting that the terminal boutons of the typeⅠ fibers might make synaptic contacts with principal neurons. The above results indicate that the projection patterns of MS/NDBV to the hippocampal formation provide new morphologic evidence for recognizing the MS/NDBV-hippocampal pathway.