Fig. 6. Eye development following lens transplantation in Astyanax mexacanus, a fish with an eyeless cave-dwelling form and an eyed surface-dwelling form. The lens of the surface fish stimulates development of the eye when it is transplanted into the optic cup of the blind cave fish. The figure shows head regions of (A to D) cave fish or (E to H) surface fish hosts shown after 2 days (A and E) and 2 months (B to D and F to H) of development. Panels A and E are ventral views, panels B and F are dorsal views, and panels C and G are lateral views. The transplant side is to the right in panels A, B, E, and F (indicated by an arrow in panel A and panel E). Panels D and H show sections through restored and degenerate eyes in cave fish and surface fish hosts, respectively. (Yamamoto Y, Jeffery WR: Central role for the lens in cave fish eye degeneration: Science 289:631, 2000)