Ring canals are structures through which intercellular material can pass from the nurse cells to the oocyte of developing Drosophila (and other Dipterans) embryos. These ring canals are actually arrested cleavage furrows yet rather than contracting and dpepolymerising as they do so as the normal cleavage furrow does, the ring canal increases in every dimention during development of the follicles (Tilney et al, 1996). A variety of proteins involved in ring canal structure and development have been identified in screens designed for mutants unable to form these structures, some of these mutants ((hu-li tai shao & Kelch) have turned out to be in genes controlling or encoding actin-binding proteins; Adducin, and Kelch (Robinson et al, 1994) respectively. Other ABP are known to be constituents of ring canals (table 1).
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