星形胶质细胞低温去分化条件

体外纯化培养的成熟星形胶质细胞经冷冻复苏方法处理后,诱导转化为放射状胶质细胞的类似细胞(RGLCs细胞).星形胶质细胞的诱导转化率与其冷冻过程的温度、时间有关.冷冻保护液中的DMSO对星形胶质细胞的诱导转化过程无关.这些结果显示冷冻复苏方法诱导星形胶质细胞的转化是由物理刺激诱导的.     

Migratory patterns of clonally related cells in the developing central nervous system

Summary Neurons and glioblasts that arise in the ventricular zone migrate to form discrete nuclei and laminae as the central nervous system develops. By stably labeling precursor cells in the ventricular zone, pathways taken by different cells within an individual clone can be described. We have used recombinant retroviruses to label precursor cells with a heritable marker, theE. coli lacZ gene; clones of lacZ-positive cells are later mapped histochemically. Here we review results from three regions of the chicken central nervous system — the optic tectum, spinal cord, and forebrain - and compare them with previous results from mammalian cortex and other regions of the vertebrate CNS. In particular, we consider the relationship between migratory patterns and functional organization, the existence of multiple cellular sources of migratory guidance, and the issue of whether a cell's choice of migratory pathway influences its ultimate phenotype.     

Cell lineage and cell migration in the developing cerebral cortex

Summary Modern techniques which trace lineages of individual progenitor cells have provided some clues about the processes that determine cell fate in the brain, and have also given us some information about migratory patterns of clonally related cells. In many parts of the central nervous system, progenitors are multipotent; single clones can contain multiple neuronal types or even mixtures of neurons and glia. In addition, one can observe a wide distribution in clone size, even when marking is done in a narrow time window. This suggests that progenitor cells may be fairly plastic and responsive to environmental signals. In the developing cortex, clonally related cells are initially grouped near each other, as in the retina and tectum. However, the subsequent migration of these cells from the ventricular zone to the cortex along glial fibers is accompanied by a progressive dispersion of clonally related neurons.     

Neuroactive steroids: State of the art and new perspectives

Neuroactive steroids include synthetic steroidal compounds and endogenous steroids, produced by endocrine glands (hormonal steroids) or the nervous tissue (neurosteroids), which regulate neural functions. These steroids bind to nuclear receptors or act through the activation of membrane-associated signaling pathways to modulate various important processes including the development of the nervous system, neural plasticity and the adaptive responses of neurons and glial cells under pathological conditions. Reviewed and updated in the present paper are the pleiotropic and protective abilities of neuroactive steroids. The fundamental evidence and knowledge gained constitute a profound background that offers interesting possibilities for developing effective strategies against several disorders of the nervous system. Received 3 September 2007; received after revision 24 October 2007; accepted 29 October 2007     

Neuronal and glial markers of the central nervous system

Summary This brief review evaluates the expression of cell-specific markers on differentiated neural cells and, where necessary, on their developing precursors. Within these limitations only the commonly used markers are discussed and those deemed unequivocal are only briefly appraised.     

Central nervous system stem cells in the embryo and adult

The central nervous system is generated from neural stem cells during embryonic development. These cells are multipotent and generate neurons, astrocytes and oligodendrocytes. The last few years it has been found that there are populations of stem cells also in the adult mammalian brain and spinal cord. In this paper, we review the recent development in the field of embryonic and adult neural stem cells. Received 26 March 1998; received after revision 27 April 1998; accepted 27 April 1998     

Getting there and being there in the cerebral cortex

The mammalian neocortex is composed of functional areas that are specified to process particular aspects of information. How is this specification achieved during development? Since cells migrate to their final positions in the developing nervous system, a central issue is the relation between cellular migration and positional information. This review combines evidence for early positional specification in the developing cortex with evidence for cellular dispersion during migration. A model is suggested whereby stable cues provide positional information and minorities of ‘displaced’ cells are respecified accordingly. Comparison with other parts of the CNS reveals that cellular dispersal is ubiquitous and has to be included in any mechanism relaying positional specification. Ontogenetic and phylogenetic considerations suggest that radial glial cells might provide the positional information in the developing nervous system.     

Mechanism of neurogenesis in adult avian brain

Summary Adult neurogenesis in birds offers unique opportunities to study basic questions addressing the birth, migration and differentiation of neurons. Neurons in adult canaries originate from discrete proliferative regions on the walls of the lateral ventricles. They migrate away from their site of birth, initially at high rates, along the processes of radial cells. The rates of dispersal diminish as the young neurons invade regions devoid of radial fibers, probably under the guidance of other cues. The discrete sites of birth in the ventricular zone generate neurons that end up differentiating throughout the telencephelon. New neurons may become interneurons or projection neurons; the latter connect two song control nuclei between neostriatum and archistriatum. Radial cells, that in mammals disappear as neurogenesis comes to an end, persist in the adult avian brain. The presence of radial cells may be key to adult neurogenesis. Not only do they serve as guides for initial dispersal, they also divide and may be the progenitors of new neurons.     

Coaxing bone marrow stromal mesenchymal stem cells towards neuronal differentiation: progress and uncertainties

Multipotent adult stem cells capable of developing into particular neuronal cell types have great potential for autologous cell replacement therapy for central nervous system neurodegenerative disorders and traumatic injury. Bone marrow-derived stromal mesenchymal stem cells (BMSCs) appear to be attractive starting materials. One question is whether BMSCs could be coaxed to differentiate in vitro along neuronal or glial lineages that would aid their functional integration post-transplantation, while reducing the risk of malignant transformation. Recent works suggest that BMSCs could indeed be differentiated in vitro to exhibit some cellular and physiological characteristics of neural cell lineages, but it is not likely to be achievable with simple chemical treatments. We discussed recent findings pertaining to efforts in neuronal differentiation of BMSCs in vitro, and results obtained when these were transplanted in vivo. Received 19 January 2006; received after revision 24 February 2006; accepted 12 April 2006     

A mechanism for macromolecular transfer from glia to neuron cell body in crayfish

Summary Small extrusions of glial cytoplasm are endocytosed by neuron cell bodies of the crayfishProcambarus. Vesicles are double walled with the external membrane issuing from the neuron and the internal one from the glia. This could be a system for the transfer of glial cytoplasmic free proteins to neurons.