金黄地鼠外侧膝状体背侧核细胞形态学及其投射神经元的确定

MORPHOLOGY OF NEURONS AND IDENTIFICATION OF PROJECTING CELLS IN THE HAMSTER DORSAL LATERAL GENICULATE NUCLEUS

用快速Golgi法研究了金黄地鼠外侧膝状体背侧核(LGd),观察了核内三种不同形态特征的神经元。第Ⅰ和Ⅲ型神经元分布在LGd各部分,第Ⅱ型则常见于LGd中份内侧。第Ⅰ型为多极神经元,胞体大,初级树突平滑但分支多,分支上布满了棘状和短柄的圆形树突突起。第Ⅱ型胞体较小,呈梨形。树突常从一主干分出,在树突分叉处分布有丛状树突突起。第Ⅲ型胞体最小。树突数目和分支也较少,但树突突起形态多样,包括如串珠样的树突突起。第Ⅰ和Ⅱ型神经元有轴突,大部分第Ⅲ型细胞则未发现有轴突。用逆行HRP法研究了LGd的三型神经元与视皮质的联系。视皮质注入HRP,标记了第Ⅰ和Ⅱ型细胞,而第Ⅲ型神经元则不被标记,说明第Ⅰ和Ⅱ型为投射性神经元。第Ⅲ型为非投射性细胞,推论其可能为局部回路神经元。

Rapid Golgi preparations of golden hamster dorsal lateral geniculate nucleus(LGd)show three classes of neurons with different morphological characteristics.ClassⅠand classⅢcells are distributed throughout the LGd.ClassⅡcells are found more common medially at mid-genieulate levels.ClassⅠcells are multipolar neurons with large cell body.The smooth primary dendrites branch extensively.Spine-like and small excrescences are found along distal dendrites.ClassⅡcells have medium size pear-like cell body.The distal dendrites are usually derived from one primary dentrite.Dense cluster of dentritic protrusions is usually found at branch points of the dendrites.ClassⅢcells have the smallest cell body and are paucidendritie but the dendrites have complex protrusions including pearl-like dendritic appendages.ClassⅠand classⅡcells possess an axon but most of classⅢcells are not found to have an axon.The connections between the LGd and visual cortex was investigated using the retrograde horseradish peroxidase(HRP)histochemical method.After injection of HRP into the visual cortex,ClassⅠand classⅡneurons were labelled but classⅢcelts were not suggesting that classⅠand classⅡcells are projecting neurons.ClassⅢcells do not seem to project to the visual cortex and are probably local circuit neurons.