Fig. 7. Separation of the telencephalic and diencephalic CPe fields. Ttr in situ hybridization on E11.5-12.5 wild-type coronal cryosections. Semi-serial sections spanning the choroid plaque and anterior diencephalon are 40-80 µm apart. (A,B) E11.5 studies. Ttr-expressing tCPe domains are separated by the Ttr-negative choroid plaque (arrow in A). No diencephalic expression is detected at this stage. (C-F) E12.5 studies. Ttr expression commences in the dCPe, which is separated from the tCPe by Ttr-negative diencephalic neuroepithelium (arrowheads in E,F). Ttr-negative choroid plaque continues to separate the bilateral tCPe fields (arrows in D,E). d, dCPe; t, tCPe. Scale bar: 0.4 mm.