Gap junctions are selectively associated with interlocking ball-and-sockets but not protrusions in the lens.

Abstract

Gap junctions are regularly associated with all ball-and-sockets examined in metabolically active young cortical fibers, but not with protrusions, in both chicken and monkey lenses. Since these unique gap junctions often protrude deeply into neighboring cells to increase membrane surface areas, they may significantly facilitate cell-to-cell communication between young cortical fiber cells. In particular, the large number of ball-and-socket gap junctions found near the equatorial region may effectively facilitate the flow of outward current toward the equatorial surface for internal circulation of ions in the lens. In contrast, a consistent distribution of high concentrations of cholesterol in protrusions would make the protrusion membrane less deformable and would be more suitable for maintaining fiber-to-fiber stability during visual accommodation. Thus, the ball-and-sockets and protrusions are two structurally and functionally distinct membrane domains in the lens.