秦岭细鳞鲑视觉器官早期发育组织学观察OA北大核心CSTPCD

Brachymystax tsinlingensis Li(1966)is sensitive to light and susceptible to death by strong light during long-term artificial breeding,especially during early developmental stages.The development of visual organs and the characteristics of retinal development were systematically observed using histological methods to analyze the physiological causes of this phenomenon and improve the efficiency of large-scale artificial breeding.The results showed that the embryo entered the organ differentiation stage,and the optic cup was formed 177 hours post-fertilization(HPF).At 213 HPF,a primitive retina and crystal sac were formed,and the cuboidal epithelium constituted the cornea.The crystal sac had developed into the lens,the cells of the neural layer of the retina had increased notably,and the staining of the pigment cell layer deepened at 357 HPF.At 452 HPF,the sclera appeared,and the retina differentiated into four layers(pigment epithelium,outer nuclear layer,inner nuclear layer,and optic ganglion cell layer).After 508 h,the fertilized egg broke the membrane and hatched larvae.The visual organs of hatchlings were relatively well-developed,and the lens is fully differentiated and has the same structure as that of the adult;the retina has been differentiated into 8 layers,and the pigment granules in the pigment layer are clearly visible;the sclera consists of elastic fibers and cartilage;the iris is in the form of a single-layer ring;and the choroid is present.At 5 days after hatching(DAH),a small number of cone cells appeared,and the visual cell layer was pure cone cell structure.At 10 DAH,the retina differentiated into a complete 10-layer structure,ON/SC was 1.27＞1,a few optic rods began to appear in the visual cell layer,and the inner nuclear layer was differentiated into three clear layers with the initial visual imaging system.At 12 DAH,ON/G was 1.07＞1,the retinal network was less convergent,and the number of nuclei in the outer nuclear layer was comparable to the number of ganglion cells,which was sufficient to receive signals from the visual cells.At 16 DAH,the mean value of the retinal bright-adapted pigmentation index(PI)was 0.75,whereas the mean value of the dark-adapted PI was significantly reduced to 0.55(P＜0.05).At 21 DAH,the number of optic rod cells increased,and the cornea differentiated into a complete 5-layer structure;at 41 DAH,the iris differentiated,the choroid was perfected,and all parts of the visual organs were fully developed.Therefore,the retinal structure and visual characteristics of B.tsinlingensis show strong light sensitivity,and vision plays a major role in its behavior and feeding activities.Reducing environmental light appropriately during early breeding of B.tsinlingensis could reduce the stress response and improve the survival rate of seedlings.The results of this study provide a reference for the proliferation,conservation,and utilization of B.tsinlingensis resources.