Restrictions in gap junctional communication in the Drosophila larval epidermis

We characterized gap junctional communication in the Drosophila larval epidermis by monitoring the pattern of dye spread following the intracellular injection of the fluorescent dye, Lucifer yellow. We found that dye injected into the epidermis spread extensively from cell to cell, but at segment borders and also at boundaries positioned at the lateral aspects of each body segment, dye spread was restricted. The precise position of these boundaries of restricted gap junctional communication was determined by examining the distribution of the fluorescent tracer in thick sections of each dye-injected specimen. These results show that each of the thoracic and abdominal segments is segregated into four domains or communication compartments. We also observed the presence of dye in the procuticle and epicuticle, and examined the possible basis for this dye localization.