斑马鱼视网膜微细结构及发育特征

Retinal microstructure and developmental characteristics in Zebrafish

目的探讨斑马鱼眼球和视网膜的微细结构及不同发育阶段的形态特征,为其作为视觉研究模型奠定基础。方法分别选取不同周龄的8组斑马鱼,每组各6条,共48条。利用光学显微镜和透射电子显微镜观察不同发育阶段的斑马鱼眼球结构,并测量视网膜各层厚度,分析其时空发育模式。从显微结构及超微结构上观察视网膜中各种细胞形态特征及神经连接方式,尤其是视杆细胞和视锥细胞的结构差异。结果斑马鱼视网膜可分为色素上皮层、视杆视锥层、外界膜、外核层、外网层、内核层、内网层、神经节细胞层、神经纤维层和内界膜等10层。与视锥细胞相比,视杆细胞的细胞核更小且电子密度更高。感光细胞终足整齐地排列在外网层,与水平细胞和双极细胞形成神经连接,并在其内观察到多条突触带。在斑马鱼视网膜中,最早发育的是神经节细胞层和内核层,随着斑马鱼的生长发育,视杆视锥层和色素上皮层厚度逐渐增长,10周左右视网膜的结构基本发育完成。结论斑马鱼视网膜形态结构典型,分层明显,神经细胞高度分化,外网层神经连接丰富。斑马鱼眼球发育特征与大多数哺乳动物相似。

Objective To study the microscopic structure and morphological characteristics of Zebrafish eyeball and retina at different developmental stages,and to lay a foundation for visual research model.Methods Select eight groups of zebrafish at different ages,with six fish in each group,48 fish in total.Optical microscopy and transmission electron microscopy were used to observe the eyeball structure of Zebrafish at different developmental stages,and the thickness of retinal each layer was measured to analyze the temporal and spatial development pattern.The morphological characteristics of various cells in the retina and the way of nerve connection were observed from the microscopic and ultrastructural aspects,especially the structural differences between rod cells and cone cells.Results The retina of Zebrafish can be divided into ten layers including retinal pigment epithelial layer,rod cells and cone cells layer,outer limiting membrane,outer nuclear layer,outer plexiform layer,inner nuclear layer,inner plexiform layer,ganglion cell layer,nerve fiber layer,inner limiting membrane.Rod cells had a smaller nucleus and a higher electron density than cone cells.Photoreceptor terminals were neatly arranged in the outer plexiform layer,forming neural connections with horizontal cells and bipolar cells,and several synaptic ribbons are clearly visible within them.In Zebrafish retina,ganglion cell layer and inner plexiform layer are the earliest developed.With the growth and development of Zebrafish,the thickness of rod cells and cone cells layer and retinal pigment epithelial layer gradually increases,and the retinal structure was basically developed in about 10 weeks.Conclusion The retinal structure of Zebrafish is typical,with obvious stratification and highly differentiated nerve cells.There are abundant neural connections in the outer plexiform layer.The ocular development characteristics of Zebrafish are similar to those of most mammals.