Functional dye coupling in ciliated RTEC. LY (A – D) or Alexa 350 (E – H) was microinjected into a single ciliated RTEC and allowed to diffuse for 5 min. Fluorescent micrographs represent typical experiments after microinjection into RTEC grown on collagen (A, C, E, G), or LM-332/collagen (B, D, F, H). Asterisks in fluorescent micrographs denote microinjected cells. The percent of microinjection experiments with dye transfer to greater than two cells after 5 min is graphed against the individual dye (I). "^" denotes a significant change in functional coupling between RTEC grown on different matrices; "*" denotes a significant change in functional coupling between RTEC grown on the same matrix with or without gap27; "#" denotes a significant difference in functional coupling as measured by different dyes; for all significance tests, P < 0.05. Values are ± standard deviation.