promotes the early dendritic differentiation of PCs and leads to increased mRNA levels of Rora1 and Rora4 at P0. (A) Quantitative distribution of PCs between stages I and IV. Cultures of P0 cerebella were kept 3 DIV in the absence or the presence of 30 nM T3. PCs are classified following the same criteria as in Figure 1. (B) P0 organotypic cultures were cultured without T3 (white bars) or with 30 nM T3 (black bars). Levels of mRNA were determined by real time RT-PCR and standardized to 18 s rRNA after 0 h, 6 h or 24 h of T3 treatment. The data are given relative to the mRNA level in untreated slices at the initial time of the culture (0 h). They were obtained from three independent cerebellar slice extracts (**P < 0.005; *** P < 0.0005). Error bars indicate mean ± standard deviation.