Absence of cell communication for fluorescein and dansylated amino acids in an electrotonic coupled cell system.

Quantitative evaluation of the diffusion process of sodium fluorescein and dansylated amino acids in the salivary gland of the larvae of Drosophila hydei reveals that the differences in specific permeability between the junctional and nonjunctional membranes, as found for small ions, do not apply to the fluorescent probes. There are no significant differences between the permeability properties for the different dansylated amino acids tested, and the same properties are found for sodium fluorescein.