Fig. 5. Cell survival test for cell clusters 9 and 10. Number of BrdU+ cells in cluster 9 (A,B) and in cluster 10 (C,D) after 7 days and 14 days of social interaction. Values are the sum of labeled cells from the two bilateral cell clusters 9 or 10 of a brain, and expressed as median ± interquartile range. (A) 7 days of social interaction did not affect the number of surviving BrdU+ cells in cluster 9 (Kruskal–Wallis test for overall difference: P=0.28). The number of BrdU+ cells in the three experimental groups doubled relative to that of the age-control animals. (B) After 14 days of social interaction, dominant animals (D) had significantly more surviving BrdU+ cells in cluster 9 than subordinate animals (S) but were not different from isolate animals (I) (Kruskal–Wallis test for overall difference: *P<0.05 (P=0.029); multiple comparison tests: P_DvsS<0.05; P_IvsD and P_IvsS>0.10). Over 14 days of survival time, the number of BrdU+ cells in the three experimental groups approximately doubled twice relative to that of the age-control animals. (C,D) The number of cluster 10 BrdU+ cells did not differ among social groups after surviving 7 days (C) or 14 days (D) of social interaction (Kruskal–Wallis test for overall difference: P_7days=0.98, P_14days=0.93). The number of BrdU+ cells in the 7-day survival groups was similar to that of the age-control animals (C), while the number of BrdU+ cells in the 14-day survival groups approximately doubled (D). (Numbers in parentheses indicate the number of animals examined.)