Research Of Relationship Between Development And Neuroapoptosis In Mouse Cerebellar Cortex

Cerebellum is posterior to the medulla oblongata and pons and inferior to the occipital lobes of the cerebrum. It is a higher-grade center of accommodation relating to carry out movement function in central nervous system. Besides,cerebellum still participate the nervous activity process of learning and memory. The mature cerebellar cortex is made up of three-layered structure including five cell types.The two most distinctive of these cell types are the giant Purkinje cells and the very small granule cells. Purkinje cells are the principal neurons of the cerebellar cortex. Granule cells are the most numerous type of neuron in the cerebellum.At present people made penetrating research on its morphous,cell chemical construction,fiber contact,neurotransmitter and the mechanism of different neuroapoptosis.But the data about the process of morphous variation and laws and mechanism of neuroapoptosis during the development in cerebellar cortex is relative less. With the problem is clarified, it will deepen the understanding of law during the nervous system development, and it will offer necessary help for embryo cerebellum transplant and some catagenetic nervous system disease.To investigate the process of histogenesis and the laws and mechanism of neuroapoptosis and their relationship during the development in mouse cerebellar cortex, light and electron microscope technology were used to observe the changes in embryonic and postnatal mice cerebellar cortex ,and the thickness and cell density of apiece layer were measured from postnatal day 2(P2) to adult mice; The neuroapoptosis of cerebellar cortex from postnatal day 0(P0) to adult mice was visualized by the active Caspase-3 PAb immunohistochemistry and Hoechst33258 staining, and Western blotting was used to study the expression of Caspase-3 and Caspase-8 in cerebellum.The results showed:①At embryonic day 12(E12),the primordium of cerebellum consists of ventricular,mantle and marginal layer;②About postnatal day 0(P0),cerebellar cortex appears a classicer laminated structure: external granular layer(EGL),molecular layer(ML),Purkinje cell layer(PCL) and internal granular layer(IGL);③The thickness of EGL becomes the most thichest at P6/7,then disappears at P20;④From P0 to P30,molecular layer primordium thickens estimating CUB curve,cell density decreases estimating S curve,IGL thickens estimating S curve, cells gradually differentiate and develop until mature,cell density increases firstly then decreases estimating CUB curve, volume of Purkinje cell increases estimating INV, density of apiece length of Purkinje cell decreases estimating S curve, the dendritic tree of Purkinje cells gradually shapes. About P7,the Purkinje cells have alignen a monolayer;the difference has statistical significance during the development in mouse cerebellar cortex, P<0.001;⑤immunohistochemistry results showed:apoptotic cells density was highest at P8,P5 and P9 in the external granular layer(EGL),Purkinje cell layer(PCL) and internal granular layer(IGL) respectively, and the density of apoptotic cells of apiece layer was lower in cerebellar cortex at P20;⑥Western blotting: Activated Caspase-3 was expressed higher at P5,then decreased gradually until P14 disappeared;Activated Caspase-8 was expressed higher from P0 to P10,about P30 disappeared;the difference about neuroapoptosis has statistical significance during the development in mouse cerebellar cortex, P<0.01.The results showed: The laminating cerebellum experiences mainly cells proliferation,differentiation and migration from E12 to P0;From P0 to P30,the laminating structure gradually develops until maturation and the external granular layer disappears gradually because of the cells migration and apoptosis,and the cells of other apiece layer are based on differentiation,development and apoptosis. It is a fastly developmental period on neurons as well as the peak period of neuroapoptosis from P0 to P14 in cerebellar cortex; Cell apoptosis pathway that Caspase-3 is activated through cleaved Caspase-8 exists during the molding and growth in mouse cerebellar cortex.