The Study Of Eye Development In Mouse And Mechanism Of Ceramide

The spinal animal eyes because of its function are a very special organ, because of its specialstructure and refractive system have been a research focus in neurodevelopmental discipline. Eye bydifferent parts of the source of several mesoderms, after a series of induction and time, a co-ordinationon the space is the formation of an organ having a precise function. Eye development includs the cornea,lens and retina development. Nerve cell migration, proliferation and differentiation are closely related. Thetopics chosen C57BL/6J mice, study the proliferation of neural stem cells of normal mice on the cornea,lens and retina during the development of nerve cells differentiation, cell apoptosis, and a special proteinexpression system from E8to E180.In addition, the studies have shown that SMS2-/-will result in the invivo accumulation of ceramide, ceramide accumulation will affect the mouse retinal nerve cell proliferationand bipolar cell development, few studies in this regard. The topics chosen SMS2-/-mice,immunocytochemistry and BrdU labeled proliferating cell technology study the issue, which will help us tounderstand the development of the retina.Objective: To investigate the effects of proliferation and apoptosis of corneal cells on the structuralrepair and modeling of the cornea; To investigate the specific functions of the cell proliferation, cell cycleand Synaptophysin expression during lens development; To investigate the relationship between cellproliferation and cell cycle during cell proliferation, cell differentiation and synaptic connections formation,as well as nerve cell differentiation and synaptic connections formation play an important role onphotosensitive information transmission; To investigate ceramide accumulation if will affect retinal nervecell proliferation and bipolar cell development.Methods: The HE stainings, immunofluorescent stainings and BrdU assay were used to observe thechanges in embryonic and postnatal of the cornea, lens and retina, and density of BrdU and CyclinD1positive cells on retinal were measured.Results:1. The histogenesis and cell apoptosis of mouse corneaDuring embryonic development and early postnatal stage, the stroma layer was observed in the developing cornea. About P14, the corneal epithelial cell layer began to proliferate and differentiate intotwo layers, with differentiation of endothelial cells. At P30we could identify the six-layer structure of thecornea. BrdU positive cells were mainly located in the fibroblasts of stroma layer and could be observed inthe corneal epithelial and endothelial cell layers after birth. With the development of the cornea, about P10the BrdU-positive cells only existed in the corneal epithelial cell layer and had disappeared in other layers.PCNA-positive cells were scattered in all layers of the cornea during the early development and distributedevenly in the basal corneal epithelial cell layer after P14, keeping a stability state. Apoptosis of cells wereobserved at every layer during early corneal development.2. Cell proliferation and Synaptophysin expression in the developing mouse lensAt about E8, the lens was evolved from the lens placode with single columnar epithelium. Then, thehollow lens bulb developed further and was filled with numerous fibroblasts, which gradually formed lens.BrdU and PCNA-positive cells were mainly distributed in the epithelium of anterior capsule. However, P10afterward, BrdU positive cells disappeared there, while PCNA continued to express in the anteriorepithelial cells a while. Cyclin D1-positive cells were mainly distributed in the epithelium of anteriorcapsule and the equator of the lens in the embryonic days and early postnatal days. After P5, CyclinD1-positive cells were mainly located in the pre-equatorial area, only few Cyclin D1positive cells werefound in the equator. Synaptophysin protein could be found to express in the matrix and some cell bodies ofequator during the development.3. Retinal neural cell differentiation and synaptogenesis in mouseEmbryos and after birth the early, Sox2and cyclind1mainly distributed in neuroblastic cell layer andthe ganglion cell layer, after P5migrating to the inner nuclear layer with the DCX, then Sox2no longerdistribution after P10and Cyclin D1no longer distribution after P14; Ganglion cells were the firstdifferentiation into mature neuron, then horizontal cells, the cone rod cells, amacrine cells, bipolar cells;DCX expressed in horizontal cells early in embryonic and postnatal mice, DCX labeled immaturehorizontal cells in neuroblastic cell layer; Early in the embryonic stage and birth SYN distributed inneuroblastic layer one-third; with the development of the mouse, SYN gradually migrated to the internaland distributed outer plexiform layer. At the same time, the SYN continued expression of the innerplexiform layer. 4. WT and SMS-/-2mouse retinal cell proliferation and bipolar cell development in contrast to thesituationWT and SMS-/-2mouse retina, BrdU and PKC-α positive cells statistics found no significant change inBrdU and PKC-α-positive cell density, the difference was not statistically significant, P>0.05.Conclusion:①First, in the developmental process of the cornea, corneal development was consistentwith the formation of its photoreceptor function, and corneal stem cell proliferation was related to itsstructural repair; a large number of apoptotic cells were involved in the structural remodeling of cornea.②Secondly, in the process of development of the lens, The cell proliferation played an important roleduring the lens development and lens repair, and cell cycle proteins Cyclin D1is probably involved inregulating the cells disappear in the equator, therefore the lens’s transparency can be kept. Synaptophysinexpression in lens has important function in lens’s transparency as well, through its regulation to calciumflow in cell bodies and matrix of lens.③In the process of development of the retina, Cyclin D1and Sox2regulated retinal progenitor cell proliferation and differentiation in retina development process to ensurethat retinal progenitor cells differentiate into neurons in opening the eyes; These cell types were born in anevolutionarily conserved temporal sequence, consistent with the differentiation and maturation of the retinafunctional maturation; synaptophysins distributed inner plexiform layer and outer plexiform layer to ensurethat the information of the photoreceptors transmitted in the vertical direction and the lateral diffusion.④The accumulation of ceramide had no effect on nerve cell proliferation and the differentiatiation ofbipolar cells in retina.