Fig. 4. Physiological colour change in vitro in eyes of sand goby, Pomatoschistus minutus.

Pigment dispersal effects of prolactin (A), ACTH (B) and α-MSH (C) after 3 h treatment. Left panel are controls incubated in MCH in Ringers solution, whereas right panel is incubated in MCH+the putative dispersal hormone for the same eye pair. Prolactin resulted in more orange coloration only compared to MCH only, whereas ACTH and α-MSH also caused melanophore pigment dispersal resulting in darker eyes. All eyes were pre-treated in MCH for at least one hour to induce pigment aggregation before addition of the dispersal hormone. Scale bar: 0.2 mm.