The mature central nervous system contains precursor cells in the subventricular 
zone of the lateral ventricle. In this study we examined the possibility to 
affect fate of precursor cells through exogenous manipulations. The results 
indicate that administration of thyroid hormone and retinoic acid increases the 
expression of Ki67, a nuclear antigen associated with cell proliferation, and of 
nestin, a marker protein for precursor cells in the subventricular zone of adult 
male rats. Moreover, retinoic acid increases polysialated-neural cell adhesion 
molecules (PSA-NCAM)-immunoreactivity. These data suggest that nuclear receptor 
ligands are potential candidates for fate determination of precursor cells in 
the subventricular zone also in the adult brain.