Figure 1.

Pigmented chimeras obtained from transplanted Mes1 cells. (A) Embryos (at day 7) of the donor (Left) and host (Right) strains. The donor, but not host, strain, shows dark pigmentation in the eye, head, trunk, and yolk sac. (B–E) Pigmented chimeras from Mes1 cells transplanted at different passages. Transplantation of cells at passage 31 (234 days of culture) (B), at passage 40 (320 days) (C and D), and at passage 36 (252 days) (E). Arrows indicate Mes1 cell-derived wild-type melanocytes in the chimeras. (B) A chimera showing a melanocyte on the head. (C and D) A chimera at different developmental stages. At day 4 (C), only a single small pigmented area is evident in the retina. By day 10 (D), expansion of this pigmented area to approximately one-third of the whole retina is paralleled by the appearance of two other pigmented areas, indicating proliferation and differentiation of Mes1 cells. (E) Pigmented chimeric fry showing melanocytes inside the head in the opercular region. (Bars = 200 μm.)