ABSTRACT
The mid-ventral third of the iris was excised from 61 adult Notophthalmus viridescens hosts, and the mid-dorsal third of the iris from donor eyes was implanted in its place. After the iris healed and the host lens was removed, two lens regenerates developed, one from the host and one from the transplanted iris. The host regenerate was removed 53-91 days after the first lentectomy. Animals were sacrificed 1-40 days after the second lentectomy. A lens developed from the host dorsal iris IN THE PRESENCE OF A NORMAL REGENERATED LENS IN 75% OF THE CASES. A large space was present between the transplant derived lens and host iris for approximately 20 days after the removal of the host lens at lentectomy 2. Stimulatory factor(s) from the neural retina could reach the competent iris through this space, inducing it to regenerate a lens. Therefore, contact between the normal lens and iris probably acts to prevent lens regeneration. In other experiments, variable amounts of neural retina from either adult or larval donors were implanted into the anterior chamber of adult newt eyes in which the lens, iris and neural retina remained in their normal relationships. Implants also contained dorsal iris, ventral iris, or no iris at all. Competent iris tissue, stimulated by the implanted retina, showed only early stages of lens regeneration, but larval retina effected a greater response than adult retina. This limited response may result from the small amount of retina in the implant, a deficiency in retinal stimulus, or a competition for the retinal factor(s) by competent iris tissues.
