Fig. 4. Quantitative representation comparing the numbers of Dlx- or Islet 1/2-expressing neurons appearing after mShhN or uShhN treatment of E11 rat telencephalic explants. The numbers of cells per 200 µm² was determined for each concentration of Shh. Four representative fields were counted for each explant; standard deviations were determined using Student’s t-test. Larger deviations at certain concentrations resulted from heterogeneity of the response within the explant (intensely labeled cells adjacent to regions of unresponsive cells).