Contacts between pigmented retina epithelial cells in culture

Abstract
The behaviour of primary cultures of dissociated embryonic chick pigmented retina epithelial (PRE) cells has been investigated. Isolated PRE cells have a mean speed of locomotion of 7·16 μm/h. Collisions between the cells normally result in the development of stable contacts between the cells involved. This leads to a gradual reduction in the number of isolated cells and an increase in the number of cells incorporated into islands. Ultrastructural observations of islands of cells after 24 h in culture show that junctional complexes are present between the cells. These complexes consist of 2 components: (a) an apically situated region of focal tight junctions and/or gap junctions, and (b) a more ventrally located zonula adhaerens with associated cytoplasmic filaments forming a band running completely around the periphery of each cell. The intermembrane gap in the region of the zonula is 6·0–12·0 nm. The junctional complexes become more differentiated with time and after 48 h in culture consist of an extensive region of tight junctions and/or gap junctions and a more specialized zonula adhaerens. It is suggested that the development of junctional complexes may be responsible for the stable contacts that the cells display in culture.