Fig. 2. Temporal requirement for kit function in regeneration melanocyte development. In situ hybridization detects kit-expressing melanoblasts (white arrowheads) in stage 4 regenerates in (A) wild type and (B) kitj1e99 mutants regenerated at 33°C, but not in (C) kitb5-null mutants (Parichy et al., 1999). (D) Histogram shows average number of pigmented melanocytes in stage 4 regenerates of kitj1e99 mutants held constitutively at 25°C (blue), at 33°C for stages 0-2 and then shifted to 25°C for remainder of experiment (black), at 33°C for stages 0-3 and then shifted to 25°C (white), and held constitutively at 33°C (red). Melanocytes indicated by white and red bars consist largely of cells that were pigmented prior to amputation and subsequently migrated into the proximal regenerate (see Rawls and Johnson, 2000). Error bars show 95% confidence intervals. (E) Stage 6 kitj1e99 regenerate shifted from 25°C to 33°C at stage 3.5. Amputation planes are indicated by black arrowheads, with distal to the right of figures. Scale bars: 20µm (A,B,C), 200µm (E).