Fig. 3. (A-E) Nuclei positive for ³HtdR alone (A,E) or 5BrdU alone (B-D). (F-J) 5BrdU/³HTdR-labeled cell nuclei. Doubly labeled 5BrdU/³HTdR nuclei, singly labeled ³HTdR-positive nuclei and 5BrdU-labeled nuclei were often juxtaposed, suggesting that their labeling resulted from a recent mitotic event (double arrows in K-M). (E,N) Singly labeled ³HtdR labeled nuclei in 5BrdU-labeled mammary tissues. Scale bar: 10 µm.