Figure 5.

(A) Time-lapse optical microscope images of flowing nodal vesicular parcels (NVPs). The orientation is indicated in the panel as left (L) and right (R). NVPs (arrowheads) are transferred to the left side by the nodal flow (Movie 5). Scale bar = 10 µm. (B) Scanning electron micrograph of the ventral surface of nodal pit cells. Red arrowheads indicate NVP precursors. Scale bar = 2 µm. (C, D) Transmission electron micrographs of nodal pit cells. (C) Transition state of NVP release in an SU5402-treated embryo. Scale bar = 1 µm. (D) NVPs (red arrowheads) are associated with microvilli (yellow arrowheads). Scale bar = 1 µm. (E) Schematic representation of NVP flow. The orientation is indicated in the panel as left (L) and right (R). NVPs appear to be released from dynamic microvilli (Movie 6), transported to the left side by the nodal flow (Movie 5), and fragmented with the aid of cilia at the left periphery of the node (Movie 7). The green halos indicate calcium elevation as a sign of cell activation on the left side of the node. (Figure modified from Tanaka et al. 2005 with permission.)