**Figure 6.** **CLs exhibit age-associated structural differences.** (**A**) Representative H&E-stained CL. The perimeter of the CL is outlined in blue. The scale bar is 50 μm. (**B**) Graph showing the area of each CL. Each data point corresponds to one CL. A t-test was performed; asterisk indicates significance (P = 0.022). (**C**) Images showing how luteinized area was determined at 40X magnification and the same images in ImageJ software. (**D**) Graph showing the average number of nuclei per defined CL area. Each data point corresponds to one CL. A t-test was performed; asterisks denote P < 0.0001. (**E**) Representative image of CD31 staining in reproductively young ovarian tissue with the boxed region in (**F**) and (**G**) representative image of CD31 staining in reproductively old ovarian tissue with the boxed region in (**H**). (**I**) Graph showing the percent of CL area positive for vasculature. A t-test was performed (P = 0.01). Scale bars are (**E**, **G**) 200 μm and (**F**, **H**) 50 μm. Data are represented as mean **±** SEM.