AbstractDevelopment of the protractor lentis muscle and the vestige of the choroid fissure, the ventral iris cleft, was studied inAmblystoma punctatumembryos, larvae and young adults. One hundred twenty‐three embryonic eyes in various stages of development were excised, rotated 180° and reimplanted to determine when in development the cleft and muscle become ventrally polarized. In Amblystoma, as the optic cup forms and the ventral region closes, the choroid fissure becomes a deep notch at the mid‐ventral rim of the cup. It remains as a cleft in the iris near the retina as the outgrowing iris obliterates the rest of the fissure. InTriturus v. viridescensthe cleft becomes located in the middle of the ventral iris membrane some distance from the ora serrata. The protractor lentis muscle arises from mesenchyme cells at the inner surface of the cornea near the cleft which it enters. InA. punctatum, the polarity of the cleft and muscle is not yet established up to stage 29. From stages 29+ to 33, when the early optic cup is forming, their polarity is labile. Polarity is permanently established soon after at stage 34.After complete ventral iridectomy the cleft reappeared in the regenerated iris. The muscle reappeared in some cases also. Retinal pigment cells locally regenerate the ventral iris and restore to it the capacity to replace a cleft which is similar to the vestigeal structure derived from the choroid fissure.This is another example where dedifferentiated retinal pigment cells restore locally to regenerating tissue the ability to form special structures normal to that re