Fig. 4. SEMs of the furrow region. (A,C) Low magnification views of cleaving embryos, with a new membrane domain appearing in the furrow region. Areas indicated by boxes are shown at higher magnification in lower panels. Bars, 100 µm and 50 µm, respectively. (B,D) Region near the center of the furrow. Note the numerous pits (arrows) with raised edges appearing in clusters (asterisks) near the furrow base. Small white structures at the base of the furrow are microvilli. Bars, 10 µm.