Figure 10.

TH specification of NPY⁺/GABA⁺ VSC annular neurons after light adaptation. A, The VSC of a larva dark adapted on a black background for 2 h and triple stained for TH, NPY, and GABA is shown in a merged image of a transverse section. Arrows indicate TH⁻/NPY⁺/GABA⁺ neurons before induction of TH. B, The VSC of a larva light adapted on a white background for 2 h and triple stained for TH, NPY, and GABA in a merged image. Arrows indicate TH⁺/NPY⁺/GABA⁺ neurons after TH induction. A, B, Stage 42. Scale bars, 30 μm. C, Quantification of the number of neurons in the VSC that express TH, NPY, or TH⁺/NPY⁺/GABA⁺. Exposure to light increases and dark decreases the number of TH⁺ neurons recruited from the NPY⁺/GABA⁺ annular pool. n = 6 larvae; values are mean ± SEM. *p < 0.05 comparing light or dark conditions with low illumination on a gray background using the Mann–Whitney U test.