Fig. 2. Blue bars, total percentage of 5BrdU-labeled cells; pink bars, percentage of ³HTdR label-retaining cells; green bars indicate the percentage of double label (³HTdR/5BrdU)-containing nuclei. After the two day 5BrdU pulse (post-pulse), 7.3±0.9% of the nuclei were 5BrdU-positive including 1.8% of the total number of ³HTdR label-retaining cells (82.8±0.9% of LREC). Following a 5 day chase (post chase), the percentage of 5BrdU-positive nuclei increased to nearly 12%, while the percent of doubly labeled ³HTdR/5BrdU nuclei dropped to 0.6%(14.7±3.0% of LREC) and the singly labeled ³HTdR-retaining cells rose to roughly 1.6% (85.2±3.0% of LREC) of the total nuclei counted. ^*The percent of LREC in the population after 5BrdU incorporation did not vary significantly, remaining near 2.0%.