Cleavage furrow formation of Rana amurensis eggs observed with fluorescence pattern photobleaching

Taking advantage of the extremely slow lateral diffusion of proteins on Rana amurensis egg surface (Xu et al., 1984), it was possible to make a sharp concentric ring pattern on the egg surface by photobleaching of the fluorescein-labelled egg surface. The shape change of the pattern reveals the movement of the egg surface. The surface, even in front of the furrow tip, is drawn towards the furrow centre. The furrow tip differentiates into border and central lines as shown by the distribution of surface protrusions. Between the border and central lines the nascent membrane inserts while the width of furrow tip increases to nearly 100 microns.