Dye transfer between cells of the embryonic chick lens becomes less sensitive to CO2 treatment with development.

Abstract

During the 3 h developmental stage 14 in the chick, intercellular transfer of iontophoresed fluorescent dyes become less sensitive to the lowering of intracellular pH by either CO2 or acetate ions. Up to developmental stage 14, dye transfer between lens cells is reversibly blocked by exposure to 50% CO2. Beyond stage 14, dye transfer between these cells is not longer reversibly blocked by elevated P[partial pressure]CO2. Electrotonic coupling is present throughout lens development and is not reversibly blocked by high PCO2 at any stage. The gap junctions joining the lens cells show morphological changes at developmental stage 14. Up to stage 14, all gap junctions observed between chick lens cells have connexon assembies that appear condensed or crystaline following routine freeze-fracture microscopy. Beyond stage 14, chick lens cells express gap junctions with bone the condensed assemblies and the dispersed assemblies characteristic of adult lens gap-junction structre.