A comparative analysis of the ventricular zone/ependymal layer in the embryonic and adult mouse spinal cord

In vertebrates, organogenesis occurs during embryogenesis. However, in many organs, stem/progenitor cells persist in specialised niches, and are/can be activated in the adult. A number of recent studies have addressed whether spinal cord stem/progenitor cells are maintained into adulthood. However, no study has yet performed a comparative analysis, asking if particular cells in the adult ependymal zone are likely to derive from the embryonic ventricular zone (VZ). Here I analyse ventricular and ependymal zones in the mouse spinal cord. My work suggests that a remnant of patterned progenitor cells, and Shh-expressing cells, may be maintained into adulthood, but in reduced numbers, and in a 'ventrally expanded' manner. My studies show that, in late embryogenesis, a Nestin+ Crb2+ radial glial-like cell forms in the dorsal-most VZ/roof plate region, and is maintained into adulthood, occupying the dorsal-most ependymal zone. My work suggests a critical function for the Nestin+ cell in mediating a transformation from VZ to ependymal zone, including changes to cell composition, marker profile and size. Although not conclusive, my data supports the idea that the Nestin+ cell exerts long-range effects on progenitor and ventral midline cells, allowing cells to migrate through and out of the VZ. This behaviour appears reminiscent of, but distinct from, EMT. Importantly, my findings suggest that the apical polarity protein Crb2 may mediate the effect of the Nestin+ cell Analyses of adult mouse spinal cord slice cultures reveals an FGF-responsive proliferative potential of lateral ependymal cells. The correlation in proliferation and loss of Shh upon culture suggests that in vivo, Shh expression in ventral and lateral ependymal cells may be crucial for maintaining ependymal cells in a quiescent state. Together these studies might provide insights into the plasticity of adult ependymal cells in both the intact and injured spinal cord.EThOS - Electronic Theses Online ServiceGBUnited Kingdo