  | 
    Figure 7: Culture 2; limbs of 8 day chicks placed in a culture of Hank’s 
      Balanced Salt Solution 1X, on Transwell (non collagen) culture inserts (24mm 
      diameter), placed in 5% CO2 incubator at 37¾C. (A) Initial state of limb 
      placed in culture; note distal (D) and proximal (P) ends of limb. Bright 
      red regions are areas of blood formation. (B) Limb after 1 week in culture 
      (day 15 for the chick) showing development of long feather buds at proximal 
      end, but no further development at the distal end. (C) Close-up of limb 
      in culture showing long feather buds.  |