**Figure 5.** **Decreased osteocyte cell volume with decreased lacunar volume in aged males but not females leads to gender differences in lacunar fluid volumes.** (**A**) Examples of 3D renderings of the osteocyte cell bodies labeled with DiO and lacunae labeled with fixable Tx-Red-dextran for volumetric calculations. (**B** and **C**) quantitation of osteocyte cell body volume in the midshaft (**B**) and distal (**C**) region. (**D** and **E**) quantitation of the corresponding lacunar volumes. (**F** and **G**) show calculation of the lacunar fluid space derived from subtracting the osteocyte cell body volume from its corresponding lacunar volume. (Data are mean ± SEM, * = p__<__ 0.05, ANOVA/Tukey’s; n= 5).