Fig. 3. Homotopic grafts in the chicken tail bud. (A) CNH, dpTB or vTB regions of stage 15 HH GFP⁺ embryos were grafted homotopically to host embryos and incubated for 48 hours. (A') Embryo immediately after a CNH graft. (A'') Mid-sagittal section of a similarly grafted embryo after 48 hours (stage 24 HH). Arrow, CNH. (B) Mid-sagittal section of the embryo in A' two hours after grafting. (B',B'') Embryo (B') and transverse section (B'') with a CNH graft at 48 hours. (C) Mid-sagittal section of an embryo with a dpTB graft two hours after grafting. (C',C'') Embryo (C') and transverse section (C'') with a dpTB graft after 48 hours. (D) Mid-sagittal section of an embryo with a vTB graft two hours after grafting. (D',D'') Embryo (D') and transverse section (D'') with a vTB graft after 48 hours. Blue, nuclear stain. Scale bars: A',B,B',C,C',D,D', 0.5 mm; A'',B'',C'',D'', 0.1 mm.