The loss of gap junctional cell-to-cell communication is coupled with dedifferentiation of retinal pigmented epithelial cells in the course of transdifferentiation into the lens.

Retinal pigmented epithelial cells (PECs) of the chick embryo can be cultured as a monolayer of melanized hexagonal cells. Modifications of the culture condition make the cells lose most of the phenotypes and further transdifferentiate into lentoid bodies within a few weeks. Ultrastructural observations showed that PECs and the lentoids have gap junctions with distinct morphology. Diffusion of a fluorescent dye confirmed the presence of gap junctions in both phenotypes. However, cells in the intermediate stage of transdifferentiation, which show neither the phenotype of the PEC nor that of the lentoid and are called dedifferentiated PECs here, have almost no gap junction structure. We propose the possibility that the dedifferentiation of PECs and the loss of cell-to-cell communication are tightly coupled events. This cell culture system is a suitable material for further studying this relationship by cellular and molecular approaches.