Figure 1. A significant expansion of BM-derived HSPCs in the middle age of female but in the old age of male mice. BM-derived lineage-Sca-1+c-kit+ (LSK) hematopoietic stem and progenitor cells were isolated via flow cytometry cell sorting, and percentages of the LSK cells among total live BM cells were compared between male and female of young, middle-aged and old mice. Multiple comparisons within 3 female groups and within 3 male groups were done separately using ordinary one-way ANOVA analysis; comparison between Yng-F and Yng-M was done using unpaired two-tailed Student’s t-test analysis. * P < 0.05, ** P < 0.01.