A demonstration of a switch of cell type in human fetal eye tissues in vitro: pigmented cells of the iris or the retina can transdifferentiate into lens

Pigmented cells of iris or retina from two human fetuses at 12 weeks after conception were cultured in vitro. In early stages of culturing (up to about 20 days), all cultured cells lost pigment granules. “Lentoid bodies” appeared at about 45 days in primary cultures of iris cells. Primary cultures of retinal pigment cells were repigmented by 30 days. When a small number of repigmented cells was transferred into secondary cultures, colonies with “lentoid bodies” were formed by 40 days. The lens nature of “lentoid bodies” was confirmed by immunofluorescence and immunoelectrophoresis using anti-rat lens serum which crossreacted with human crystallins.