Inhibition of Lens Regeneration by Nickel Subsulfide in the Japanese Common Newt, Cynops pyrrhogaster

To investigate the effects of nickel subsulfide (Ni₃S₂) on lens regeneration, Ni₃S₂ was administered to the lentectomized newt eye by a single injection into the eye chamber. Lens regeneration was inhibited in the early stage of regeneration with about 60% of the treated eyes after 25 days, while all control eyes had a regenerating lens. The size of the regenerating lens in the treated eyes was the same as in controls. Lens regeneration was inhibited in all treated eyes containing Ni₃S₂ particles within the eye chamber. Inhibition of lens regeneration in the treated eyes was about 80% at 3 months, when all control eyes had already completed lens regeneration. Although the tendency toward pupil disappearance was prominent in the eyes having no regenerating lens, there were also a few eyes which had no regenerating lens and no signs of pupil disappearance. The significance of these results was discussed in relation to the regeneration and carcinogenesis.