Morphological Studies On The Developing Retinal Ganglion Cells In The Chick Embryo

80 percent of the outsider information obtained by the brain is through the visual system. All of the vision information that projects to the eyeball is through the unique retina ganglion cells to the brain. Therefore, development of the retina ganglion cell is beneficial to clarify the sense of vision formation mechanism. On the other hand, Chickens posses highly developed visual performance. So light is one of the most effective factors to productive performance of chickens. This study promotes poultry industry, and has the important and realistic meaning.Chickens were used as experiment animal model. The development of retina ganglion cells and the distribution of dentrite in the inner plexiform layers of retina of chick embryo were examined. The morphology of ganglion cell was observed by retrograde labeling of cargocyanine dye(DiI) and the confocal microscope.Result indicates as followings (1) The retina ganglion cells, small in number in form of "bud", appears only at the central retina firstly at 6 days of incubation (E6), sequentially the retina ganglion cells progressively develop, mainly as small soma,and dendrite with sparse branch at E8. The soma of retina ganglion cell grow mainly medium and small, up to E10-11, and is divided into five types, namely narrow dendrite field with simple dendritic arborization and small somal area (Is-like cell), narrow dendrite field with complex dendritic arborization and small somal area (Ic-like cell), middle-size dendrite field with simple dendritic arborization and middle-size somal area (IIs-like cell), middle-size dendrite field with complex dendritic arborization and middle-size somal area ( lie-like cell) wide dendrite field with simple dendritic arborization and middle-size somal area ( Ills-like cell), respectively,up to E13, retina ganglion cell is devided into six type. The process of retina ganglion essentially completes at 20 days of incubation, and 6 types of retina ganglion cells appear as followings, Ic cell, IIs cell,IIe cell, IIIs cell and IVc cell (wide dendrite field with complex dendritic arborization and wide somal area), respectively. (2) Ganglion cells layer is seen in the central retina at E8, the development completes at E14 (3) The growth of the inner plexiform layer begins from E8 in the central retina; sequentially develop in the peripheral retina. The inner plexiform layer thickens continuously. The development of the inner plexiform layer contains two periods of fast development, namely E8 to E10 and E16 to E20. (4) The growth mode of ganglion cell dendrite is in accordance with that of the innerplexiform layer. The dendrite stretch into the different sub-layer of the inner plexiform layer at E16. The developnment process of dendrites of ganglion cell completes at E20.Conclusion: The ganglion cell layer appears firstly at E8. Six distinct morphological types of ganglion cell differentiate at E13 to E14. The ganglion cells mature at E20.