Development of retinal photoreceptor cell layer during visual transition in mandarinfish Siniperca chuatsi
ZHANG Ruiqi1,2, 3,ZHANG Yan4,ZHAO Jinliang1,2,3*
1.Key Laboratory of Freshwater Fishery Germplasm Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China; 2.Shanghai Collaborative Innovation for Aquatic Animal Genetics and Breeding, Shanghai 201306, China; 3. National Demonstration Center for Experimental Fisheries Science Education, Shanghai 201306, China; 4.Shanghai University of Engineering Science, Shanghai 201306, China
Abstract: Growth pattern and cone mosaic in retina were investigated in mandarinfish Sinipercachuatsi during three stages of visual transition period (D28(28 days post-hatching), body length of 25-35 mm, D42(42 days post-hatching), and D63(63 days post-hatching), body length of 85-100 mm) by means of histological method, immunofluorescence and geometry analysis in order to evaluate the retina photoreceptor layer structural changes in mandarinfish during the visual transition period. It was found that there was significant increase in number of rod cells during the visual transition period, 4 500-6 000 cells/100 μm2 in each area in D63; slow increase in the single cone cell (SC) number, 20-40 cells/100 μm2 in D28, only 5-8 cells/100 μm2 in D63. Meanwhile, there was more rapid growth of double cone cell (DC) than that of SC, with 70-100 cells/100 μm2 in D28, and 100-150 cells/100 μm2 in D63, as a whole the DC/SC ratio was decreased, close to 50 in D63. There was better growth of cone cells in the ventral side than that in the dorsal side, and the rod cell rapid growth did not affect cone mosaic formation. The structure of retina photoreceptor layer was changed dramatically during the visual transition period, with significant change in number and proportion of all kinds of photoreceptor cells. There were evenly development of rod cells and regionalization growth of cone cells, with two development events independent of each other which together to provide a structural basis for its visual transformation. The findings indicated that the photoreceptor layer of mandarinfish retina was changed dramatically in the visual transition period, the rod cells grew evenly in all regions, and the cone cells on the ventral side grew faster than that on the dorsal side. These developmental characteristics of photoreceptor cells provide the structural basis for the visual transformation of mandarinfish in benthic living habit under dim environment.
2021, Vol. 36 
