The Study Of Mouse Cajal-retzius Cells’ Histogensis And Expression Of The Cell Cycle-related Proteins

In the development of the neocortex and hippocampus,Cajal–Retzius (CR) cells play a critical role. Theirfunction is to regulate the formation of cortical layers by secreting Reelin. CR cells have also can maintainthe phenotype of the radial glia, and may regulate the formation of the neural circuit through electricalactivity and neurotransmitter secretion. Reelin is a large glycoprotein that acts as a signal to regulate themigrations of the newborn neurons by regulating the receptor molecules VLDLR and ApoER2. Loss ofReelin activity, as occurs in the mouse mutant strain reeler and in rare human neurological cases, causessevere malformations of the cortex as well as the cerebellum.CR cells have no apparent functions in themature cortex, and most undergo apoptosis after the cortical layers have formed.Objective: To study Cajal-Retzius (CR) cells’ histogenesis and their expressions of cellcycle-related proteins in mouse.Methods:Immunofluorescent labeling and BrdU assay were carried out at various embryonic andpostnatal ages.Results:①The birthday of CR cells was at about embryonic day10(E10) or11(E11). CR cellsmainly distribute in the molecular layer of neocortex and hippocampus. Their number decreased with ageincreasing.②From E15to adult, Cyclin A2, Cyclin E1, and CDT1were expressed continuously inCR cells, but there is no any expression of Cyclin D1in CR cells.Conclusions:①CR cells plays a vital role in the mouse brain neocortex development. The migration ofneurons in the mouse brain is at E11-E16, in the same time the CR cells secreted Reelin as a guidance of neuronal migration of molecular signals. CR cells must be generated in the early stage of brain development(E10, E11), so as to ensure that neuronal migration could not making a mistake.②Start ing from the E15,the density of CR cells showing decreasing trend gradually for two reasons: First, the CR apoptosis lead toits number decreasing. Second, the brain surface area is increasing when brain development, while thenumber of CR cells is decreased rather than increased.③The intermediate neurons which express of Reelinmigrate from the bottom up into the layers of the neocortex. They should play as a instead of CR cells andas the main role of the sources at Reelin secretion, and these Reelin mainly to continue guiding newbornneurons from the SGZ and the SGZ generate and modifing neural network.④CR cells is in the G0phase,Cyclin A2and cyclin E1plays a role protecting CR cells, in case of the abnormal cell cycle start. cyclin D1mainly exist in the glial cells which can be split and leptomeningeal cells.