Rates of diffusion of fluorescent molecules via cell-to-cell membrane channels in a developing tissue.

Diffusion coefficients for the intercellular movement of fluorescent tracers have been measured in the epidermis of a larval beetle. Fluorescent tracer was injected into a cell and the spread of tracer from cell to cell in this monolayer was recorded by a TV camera. Fluorescence intensities were digitized from the TV images at successive times after the start of injection at various distances from the source by a microcomputer interfaced with a …