Vimentin intermediate filament protein as differentiation marker of optic vesicle epithelium in the chick embryo

For the study of the differentiation process of optic vesicle; epithelium i nto neural retina, pigment epithelium and pars caeca retinae, vimentin inte rmediate filament protein in retinal epithelial cells was detected immunohi stochemically in chick embryo at stages 11-21. In the late stage of optic v esicle development (stage 14), optic vesicle epithelium was classified into the following 3 different portions on the basis of vimentin staining inten sity: latero-central epithelium under the lens placode, medio-central epith elium facing the latero-central epithelium, and peripheral epithelium conne cting the latero-central and medio-central epithelia. Latero-central epithe lium, the future neural retina, exhibited: strongest staining of vimentin o f the 3 portions. In contrast, medio-central epithelium, the future pigment epithelium, showed weakest staining. Moderate staining was observed in per ipheral epithelium, the future pars caeca retinae. These differences in lev els of vimentin expression were observed during optic cup formation. The pr esent results: clearly demonstrate that differentiation of retinal epitheli um into neural retina, pigment epithelium and pars caeca retinae occurs in the late stage of the optic vesicle, and that retinal differentiation is re flected by the amount of vimentin in epithelial cells.