Reduced macrophage phagocytic activity in Wolffian lens regeneration of the newt after nickel subsulfide administration.

The inhibition of newt lens regeneration by intraocular injection of nickel subsulfide (alpha Ni3S2), a potent carcinogen, was shown in our previous studies. In the present study, we examined the effect of nickel subsulfide on macrophages involved in depigmentation in the early stages of regeneration using light and electron microscopic observations on semithin (1.5 microns) and ultrathin sections. Phagocytic activity of macrophages in ingestion of pigment granules from pigmented dorsal iris epithelial cells was much reduced in the carcinogen-treated eyes, whereas the change in their number and pattern accumulating in the iris during lens regeneration was generally the same as in untreated eyes.