Figure 4

Patterns of cell proliferation in response to wound healing. Longitudinal sections were labeled with an antibody against BrdU (green) and Hoescht dye (red) to determine cell proliferation in the longitudinal muscle (LM) and coelomic epithelia (CE). (A) Actively dividing cells were mainly observed in the coelomic epithelia proximal to the injury at 6 dpi. Note that not only the number of dividing cells appears higher but the coelomic epithelium has increased in width. Some cell division is also observed in the muscle layer (arrows) (B) An area distal to the injury site shows much less cell proliferation and a thinner coelomic epithelium. (C) Control (sham-operated) animal at 6 dpi only shows modest cell division and a very thin coelomic epithelium. (D) Minimal cell division is observed at 20 dpi suggesting the stage-dependent role that cell division plays in wound healing. (E) Quantification of cell division at the injury site shows a peak in cell proliferation at 6 dpi. (F) The coelomic epithelia of experimental animals show the largest percentage of diving cells also peaking at 6 dpi. Values of control animals increase slightly but remain significantly lower than experimental animals. (G) Cell division in the longitudinal muscles follows a similar pattern with a sudden peak in cell division at 6 dpi, however the percentage of proliferating cells is much lower than for the coelomic epithelium. CE-coelomic epithelia, LM-longitudinal muscle. PE-Proximal epithelium, PE-C Proximal epithelium-Control, PM Proximal muscle, PM-C Proximal muscle-Control. Bar = 25 μm. Each point represents the mean ± S.E. of at least three animals. *p < .05, **p < .01.