鸡投射视顶盖视网膜节细胞的形态学分类

MORPHOLOGICAL CLASSIFICATION OF RETINOTECTAL GANGLION CELLS IN THE CHICK RETINA

目的 研究鸡视网膜 视顶盖投射系母体———视网膜节细胞 (RGCs)的形态学类型。方法 用逆行追踪法标记鸡投射至视顶盖的RGCs,再用细胞内注射法将标记的RGCs的全树突可视化 ,根据其细胞体和树突野的大小和树突分支特征进行形态学分类。 结果 鸡投射至视顶盖的RGCs可分为 3群、5亚群 ,即小细胞体和小树突野的I群细胞 ,包括简单型的Is亚群和复杂型的Ic亚群 ;中等细胞体和树突野的II群细胞 ,包括IIs和IIc两亚群 ;具有巨大的细胞体和树突野的IV群细胞 ,仅见IVc亚群。各亚群的比例分别是 :Ic 2 7 7%、Is 33 6 %、IIc 2 5 %、IIs 2 4 4 %、IVc 11 8%。 结论 投射至鸡视顶盖的RGCs以中小型细胞为主 (约占 88 2 % )和一部分大型细胞 (占11 8% ) ,其中Ic亚群细胞类似于哺乳动物的 β节细胞 ,而Is和IIs亚群细胞在哺乳动物尚未见报道 。

Objective To study the morphological types of the retinal ganglion cells (RGCs) projecting to tectum in the chick. Methods The tectal projecting RGCs in the chick were identified by retrograde axonal transport of Fast blue and their dendrites were labeled by intracellular injection of Lucifer Yellow.The retinotectal projecting ganglion cells were classified according to somal areas,dendritic field sizes and dendritic branching pattern. Results Retinotectal projecting ganglion cells were divided into 3 groups and 5 subgroups,Group Ic/Is,Group IIc/IIs,Group IVc.Group I cells had small somal area and small dendritic field.They contained 2 subgroups of Is(simple)and Ic(complex).Group II cells had medium sized soma and dendritic field,and also included 2 subgroups of IIs and IIc.Group IV cells had large soma and dendritic field,and only contained a subgroup IVc.The proportion of each subgroup was 27.7%(Ic),33.6%(Is),2.5%(IIc),24.4%(IIs),and 11.8%(IVc),respectively. Conclusion The types of retinotectal projecting ganglion cell were prominently composed of small to medium sized neurons(88.2%)and some large neurons(11.8%).Ofthese,subgroup Ic cells which were very similar to β cells were found in the chick and subgroup Is and IIs were not reported in the mammalin retina.The cells in group Ⅲ,which were found in the chick central retina,did not project to the tectum. [