The Interaction Between Cell Migration And Vasculature In The Developing Cerebellum Of Mouse

The traditional theory was that immature neurons primarily migrated to the final destinationalong the radial glial cells. Radial glial cells were ubiquitous during the process of developing of vertebrateanimal central nervous system which are also called bergman glial cells (Bergmann glia cell), and were akind of glial cells, embryonic stem cells. They can develop into astrocytes and granular cells in thecerebellum cortical development process. Therefore, radial glial cells played an important role in the centralnervous system. They could not only guide the migration of neurons from ventricular zone to after mitoticdivision area, but also probably served as scaffolds for the neuronal migration. But recently more and morestudies have shown that blood vessels were also involved in the neuron migration in the central nervoussystem. Vessel’s main function was to transport some gas, nutrients, hormones and circulating cells. Theblood vessels in the nervous system have a wide range of functions, for example,“vascular niche” in theearly embryos could provide a "micro environment" for neurogenesis, nerve cell migration and axonextensions.At present, people had done a lot of researches in the development of cerebellar cortex, cellmorphology and neurotransmitter, but during the developing process of cerebellum cortical, the relationshipbetween blood vessels and the cell migration was not very clear. In addition, studies had shown thatsphingomyelin synthetase2knockout (sphingomyelin synthase2knockout, SMS2-/-) in mice would causeceramide accumulation in the body. Whether the accumulation of ceramide would affect the cerebellumgranular layer cell proliferation was not clear. Therefore, the further clarification of this problem made usdeeply understand the developments of the central nervous system and the diseases related to them, at thesame time help treat some clinical diseases of retinal nerve tissue and blood.Objective: Our aim is to observe the developing process of mice cerebellar cortical and radialglial cell differentiation; To explore the relationship among blood vessels, radial glial cells and cellmigration; Analyse the effects that ceramide accumulation had on neural cell proliferation in the granularlayer of cerebellar.Methods: The immunofluorescence, BrdU and ink perfusion were used to take on morphological observation of cerebellar cortex from embryonic to postnatal mice. Compare and measure BrdU positivecell number in the granular layer and cerebellar cortex vascular volume density in C57BL/6J mice andsphingomyelin synthetase2knockout mice.Results:(1) Lamellar formation of cerebellum: development of cerebellum in mice began fromthe rhombic lips in the fourth ventricle wall. At E0, lip was mainly composed of neuroepithelium, and at P0,cerebellar cortex formed the outer granular layer, molecular layer, purkinje cell layer and granular layer. Asthe growth of the age, at P3, purkinje cell layer was on disorder, about3-6layers, and at this time cellsmigrated from the outer granular layer to inner granular layer. At P10, cells in the outer granular layer hadmigrated to inner granular layer. About at P22, cerebellar slices change had completed, which formed threetypical structure: molecular layer, purkinje cell layer and granular layer.(2) The cell migration: At aboutE15, purkinje cells began to migrate, and at P7they completed their migration, arranging a layer. At thesame time, cells in the outer granular layer began to migrate to inner granular layer at P0, and up to P10,the migration grounded to a halt.(3) Radial glial cell differentiation: At E15, a lot of radial glial cellsappeared in cerebellum, and along with the development of cerebellar cortex, up to around P14, radial glialcells completely differented into astrocytes.(4) The relationships among blood vessels, radial glial cells andcell migration in the cerebellum: Ink perfusion method showed that vascular volume density in thecerebellum was on a rising trend. Correlation analysis indicated that the correlation coefficient is0.992, P <0.05, and it showed that age of mice and vascular density is highly relevant. At E15-P7, the course anddistribution of blood vessels and radial glial cells in the cerebellum remained consistent, and thearrangement of molecular layer is in order, but in granular layer and white matter, the course anddistribution of blood vessels and radial glial cells is in disorder. In addition, the study also showed thatmany BrdU-positive cells could migrate along blood vessels.(5) Comparison between WT and SMS2-/-mice: BrdU antibody can specially label the cells in S phase proliferation. Based on BrdU positive cellnumber in the cerebellar cortex from WT and SMS2-/-mice at P0-P14, we found BrdU positive cell densityhad no significant change between them, the difference was not statistically significant, P>0.05. Inaddition, there were no significant differences of WT and SMS2-/-mice cerebellum in morphology, cellmigration and angiogenesis.Conclusion: Cerebellar lamellae formation process of mice mainly experienced cell proliferation, differentiation and migration. Cell migration plays a crucial role in cerebellar lamellae formation process, atthe same time we found that the blood vessels not only have interaction with the radial glial cells, but alsoguide the migration of neurons in the cerebellum, probably serving as scaffolds for the neuronal migration.The accumulation of ceramide had no effect on nerve cell proliferation in cerebellum.