Fig. 3. Olomoucine increases the proportion of neuron-generating NE cells. (a,b) Composite showing TIS21 immunofluorescence in sagittal cryosections through the spinal cord (sc), hindbrain (hi), mesencephalon (me) and telencephalon (te) of E9.5 littermate embryos developed for 24 hours in WEC in the presence of 80 µM iso-olomoucine (iso-olo, a) or olomoucine (olo, b). (a',b') Corresponding phase contrast images shown at lower magnification. Filled arrowheads in b indicate areas of the telencephalon prematurely expressing TIS21. Scale bar: 400 µm. (c) Quantitation of TIS21 immunoreactivity. The region of the telencephalon indicated by the dotted lines between the open arrowheads numbered 1 and 24 in a and b was divided into 24 segments of similar area, and the fluorescence in each area was quantitated; a.u., arbitrary units. Filled circles, iso-olo; open squares, olo. Graphs in d and e show a similar quantitation of the TIS21 immunoreactivity shown in Fig. 4a and b (segments 1-22 corresponding to bottom-to-top) and Fig. 4c and d (segments 1-23 corresponding to top-to-bottom), respectively.