Figure 7. Comparisons of select sex hormone concentrations in serum between male and female of young, middle-aged and old mice. Peripheral blood was collected from indicated mice and serum was prepared for ELISA assay. Concentrations of (A) follicle-stimulating hormone, (B) estrogen and (C) androgen in serum between male and female of young, middle-aged and old mice. * P < 0.05, ** P < 0.01, *** P < 0.001.