INTERCELLULAR BRIDGES BETWEEN EPITHELIAL-CELLS IN THE DROSOPHILA OVARIAN FOLLICLE - A POSSIBLE AID TO LOCALIZED SIGNALING

In the epithelium of Drosophila ovarian follicles, cytoplasm-filled in tercellular bridges connect epithelial cells. This study presents furt her descriptive information about the morphology of these intercellula r bridges and the extent of their distribution. We also offer speculat ions concerning the possible developmental importance of the epithelia l bridges. These bridges,,whose luminal diameters averaged 0.25 mu m, are smaller than those forming the ring canals joining germline cells: nor do they increase their size over time. The membranes limiting the bridges are lined on the cytoplasmic side with an electron-dense mate rial to which is attached a monolayer of filaments which encircle the bridge. By decoration with the S1 fragment of myosin, these filaments are confirmed as actin filaments. Following disruption of gap junction al dye coupling by treatment with 1 mM octanol, microinjection of Luci fer yellow CH revealed the extent and distribution of follicle cell in tercellular bridges to be confined to arrays of no more than eight cel ls/cluster, with many such independent clusters comprising the epithel ium. Thus cell-to-cell movement throughout the epithelium of cytosolic regulatory molecules cannot occur via these intercellular bridges. Ho wever, weak signals affecting only one or a few cells in each cluster would be amplified throughout the group by spread through the intercel lular bridges. (C) 1998 Academic Press.