Fig. 8

Quantification of cell proliferation in the four terminal arm segments O. brevispinum. (a) Dual pulse labeling paradigm. The animals were first pulsed with EdU, followed by a 7 day chase period, then pulsed with BrdU and processed for microscopic analysis. Both pulses lasted 4 h. (b, c) Boxplots showing individual data points and pairwise P values from the Wilcoxon-Mann-Whitney test. (b) Abundance of dividing (BrdU-incorporated) cells (per \(\mu\)m\(^3\)). (c) Relative abundance of repeatedly proliferating cells (i.e., those that have incorporated both thymidine analogs) measured as the percentage of proliferating cells undergoing the second round of cell division (i.e., the cells that have incorporated both EdU and BrdU). (d–f’) Representative micrographs showing distribution of labeled cells in the arm tip. Maximum intensity Z-projections of confocal stacks. Aboral-oral view. Boxed areas in d, e, and f indicated regions showed at higher magnification in d’, e’, f’, respectively. Arrowheads indicate dual-labeled EdU\(^+\)BrdU\(^+\)-cells t—terminal segment; s\(_2\)–s\(_4\)—arm segments 2 thru 4, as counted from the distal tip of the arm (outlined by dashed lines in d’, e’, f’)