For dye-permeability assays, 10 kDa Dextran-TR (Thermo Fisher Scientific) was injected into late stage 16 embryos (after the maturation of SJ) as described in Jayaram et al., 2008 (link). Injections were performed in a microinjection system (FemtoJet, Eppendorf) coupled to an inverted fluorescence microscope (Cell Observer, Zeiss).
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