Fig. 9. F-actin organization within the notochord. Each image is a projection of 5 confocal sections taken at 0.2 µm intervals. (A) Top view section through a mid-stage II embryo (approx. 17 hours AF) illustrating general F-actin organization within the notochord plate and surrounding tissues. The interior cytoplasm of each notochord cell is filled with a dense meshwork of F-actin except where excluded by yolk granules (small dark holes) or nuclei (*). F-actin puncta similar to those described elsewhere (Foe et al., 2000; von Dassow and Schubiger, 1994) appear throughout the cytoplasm. Posterior is to the left. (B,C). Cross-sectional views of stage II embryos showing actin-rich protrusions (arrows) extending across the surfaces of adjacent neighbors. In C a protrusion lies just out of focus and to its right can be seen a dense meshwork of F-actin fibers in the cortex of the cell across which it is extending. Dorsal is up in B and C. Scale bar, 10 µm in all panels. B and C have same scale.