Fig. 2

RNA aggregates lie along a filamentous network, which undergoes movement towards the periphery and circumferential alignment. Animal views of embryos fixed at progressively older stages of development (A–C: 15 min p.f.; E–G: 30 min. p.f.; I–K: 45 min p.f.) and labeled using FISH to detect nos1 RNA. Panels A–C, E–G, and I–K are progressively higher magnifications of the same embryo (left column: overview; middle and left columns: square in the middle panel is shown in the right panel at a higher magnification). As development proceeds, the diameter of the RNA-free region increases (dashed double ended arrows in A, E, I) and the width of the RNA-rich band decreases (solid double ended arrows in A, E, I), reflecting the movement towards the periphery of RNA aggregates closest to the center of the blastodisc. High magnification views show that RNA aggregates lie along a filamentous network (C, G; traces along a subset of lines of aggregates in these panels are shown in D, H, respectively). The original orientation of the lines of aggregates appears random, but upon development, they tend to align circumferentially (arrowhead in G; arrows in B–D and F–H point to the center of the blastodisc). As these processes occur, the size of the RNA aggregates increases (arrowheads in J, K). Furrow formation accompanies germ plasm recruitment at the furrow (arrows in J, K), which is typically flanked by regions free of RNA aggregates (brackets in K). Scale bar in (K) represents 100 μm (left column), 50 μm (middle column), and 16 μm (right column).