Transcription Factor Codes that Specify Neuron Class-Specific da Dendrite Arbor Shape. Tracings to illustrate the dendrite arbor morphology of the four classes of da neuron: class I ddaE, class II ddaB, class III ddaF and class IV ddaC at wandering third instar stage. Anterior is to the left, dorsal is up, the scale bar is 75 µm. The expression of the different class-specific transcription factors is shown. For Cut: − no protein expression, + low, ++ intermediate, +++ high. This figure is reproduced with modifications from Jinushi-Nakao et al. (2007).