ABSTRACT
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.
ABSTRACT
This study was performed to investigate whether the kinds and arrangement patterns of the cone cells were related to the kinds of behavior, prey and habitat in the species of genus Zacco and genus Pseudogobio The retinas were observed by a light microscopy using H-E staining method. The cone cells of Z. platypus and Z. temmincki showed compact mosaic patterns of row type. Keep apart from the center, the diameters of the double and single cone cells were gradually increased. Z. temmincki developed the identical double cone cells, and Z. platypus developed the non-identical double and single cone cells. But, Pseudogobio esocinus constituted loose mosaic patterns of row and irregular types and developed the identical double cones and single cone cells. The above results suggest that the kinds and mosaic pattern of cone cells of Z. temmincki feeding on a moving aquatic insects in relative limpid water and swift current, reflect the highest resolution among these three species. And the kinds and mosaic pattern of cone cells of P. esocinus keep watching around in the sand ground and feeding on a moving aquatic insects in relative limpid water and gentle current, suggest that if has better resolution than those of Z. platypus feeding on mainly adhesive algae and some aquatic insects in slightly turbid water.