The electrical coupling of epithelium and fibers in the frog lens

Electrical coupling has been measured between central epithelial cells and fiber cells in the frog lens following the removal of the lens capsule with collagenase. Current passed from a microelectrode inserted in a lens fiber cell was found to induce a potential difference in epithelial cells which was indistinguishable from that measured in nearby fiber cells. The measurements were made under circumstances where the current and voltage microelectrodes could be shown to be in different cells and an intraepithelial location of the voltage-measuring microelectrode could be verified. The electrical coupling appears to be direct from superficial fiber cells to epithelial cells, rather than indirect through equatorial epithelial cells. The epithelial cells and surface fiber cells each had resting potentials of -61.8 +/- 2.1 mV in this collagenase-treated preparation. Scanning electron microscopy (SEM) of mechanically decapsulated frog lenses showed specialized junction-like plaques on the expanded anterior ends of fiber cells which made contact with epithelial cells. Such specialized plaques were not found on the expanded posterior ends of these fibers where they contracted the posterior capsule. The studies provide direct evidence for cell-to-cell communication between frog lens epithelial cells and fibers.