[On the ultrastructure of proliferative changes (cell metaplasia) in the retinal pigment epithelium over malignant melanomas of the choroid (author's transl)].

Proliferations of the retinal pigment epithelium over malignant melanomas of the choroid from three human eyes were examined at various locations: 1. at the posterior pole, 2. in the equator region, 3. at the ora serrata. The observation was made that in each proliferation one cell type dominates which could be distinguished by its shape and cytoplasm from those of the other proliferations. Only the cells of the proliferation at the posterior pole correspond with the normal pigment epithelium. Most of the cells in the equator region show several properties of glia cells whereas these of the ora resemble fibroblasts. Our findings suggest that the proliferated pigment epithelium over malignant melanomas of the choroid is capable of undergoing metaplastic changes.