Figure 10

Formation of spindle-like structures (SLS) by muscle cells during intestinal regeneration. Double labeling of muscle fibers and SLS with rhodamine-labeled phalloidin (green) and cell nuclei with DAPI (red). (A) At 1-dpe, muscle fibers have disappeared from the tip of the mesentery (brackets) and SLS (arrows) are found close to the remaining muscle fibers (arrowheads). (B) At 5-dpe, the intestinal rudiment and adjacent mesentery are devoid of muscle fibers but some SLS (arrows) are present. (C) At 7-dpe, the area of the mid mesentery has SLS (arrows) and a few remaining muscle fibers (arrowheads), while (D) the mesentery close to the body wall has abundant muscle fibers (arrowheads) and only a few SLS (arrows). Bar = (A&C) 65 μ m, (B) 125 μ m, (D) 25 μ m. (E) The number of SLS was measured in different areas (corresponding to ~40,000 um²) of the intestinal rudiment and mesentery in regenerating animals from 1 to 28-dpe. In the mesentery adjacent to the rudiment, SLS show an increase from 1-dpe, peaking at 5-dpe. Areas of the mesentery distant to the regenerating structure (medial and distal) show a smaller amount of SLS and a peak at later stages. Each point represents the mean ± S.E. of at least three animals. ANOVA analysis showed significant differences in the mesentery adjacent to the rudiment. Asterisk show the results of t-test comparisons of different stages to dpe-28 *p < 0.05. **p < 0.01. ***p < 0.001.