Unique neuronal tracers show migration and differentiation of SVZ progenitors in organotypic slices

Continual neurogenesis in the subventricular zone (SVZ) of postnatal and ad ult mammalian forebrain has been well documented, but the mechanisms underl ying cell migration and differentiation in this region are poorly understoo d. We have developed novel in vivo and in vitro methods to investigate thes e processes. Using. stereotaxic injections of a variety of tracers/tracker [Cholera Toxin beta subunit (CTb-), Fluorogold (FG), and Cell Tracker Green (CTG)], we could efficiently label SVZ cells. Over several days, labeled c ells migrate along the rostral. migratory stream (RMS) to their final diffe rentiation site in the olfactory bulb (OB). The compatibility of these trac ers/trackers with immunohistochemistry allows for cell labeling with multip le dyes (e.g., CTb and CTG) and/or specific cell antigens.. To investigate the dynamics of migration we labeled SVZ progenitor cells with small inject ions of CTG and monitored the movements of individual cells in fresh parasa gittal brain slices over several hours using time-lapse confocal microscopy . Our observations suggest that tangential cell migration along the RMS occ urs more rapidly than radial cell migration into the OB granule cell layer. To investigate migration over longer time periods, we developed an in vitr o organotypic slice in which labeled SVZ progenitors migrate along the RMS and differentiate within the OB. The phenotypic characteristics of these ce lls in vitro were equivalent to those observed in vivo. Taken together, the se methods provide useful tools investigating cell migration and differenti ation in a preparation that maintains the anatomical organization of the PM S. (C) 2001 John Wiley & Sons, Inc.