Fig. 4. KITL rescues melanoblast differentiation in Ednrb^lacZ/Ednrb^lacZ neural crest cells. Primary cultures from embryos of the indicated genotypes were established and kept in the presence of KITL for 2 weeks before fixation. The cultures were then double-labeled for ß-gal and tyrosinase as described in Fig. 2. Note the presence of Tyr/ß-gal double-positive cells in KITL-treated cultures, regardless of whether they were derived from Ednrb^lacZ/+ (A) or Ednrb^lacZ/Ednrb^lacZ embryos (B). Scale bar: 25 µm.