Fig. 1. Dilated furrow canals in embryos from RhoGEF2 and dia germline clones. (A) Schematic drawing of cellularisation showing the furrow canal, basal junction and plasma membrane. Embryos prepared for TEM by high pressure freezing and freeze substitution. (B) In the wild-type embryo, furrow canals are seen as a dilatation of the plasma membrane growing in from the apical surface. In embryos from (C,D) RhoGEF2^1.1 and (E,F) dia germline clones, furrow canals are considerably enlarged and filled with large cytoplasmic blebs (arrows in C,D,E). No simple hairpin structure can be seen in most of the cases. Apical side up. Scale bars: 0.5 µm.