Representative sections showing ovaries from mature Zucker fa/fa rats with multiple cysts. a) HE staining. b) TUNEL. c) Immunohistochemical staining of anti-factor VIII. d) negative control (TUNEL). e) negative control (anti-factor VIII). Arrows show TUNEL-positive atretic follicles; arrowheads show cysts within interstitial cells. Factor VIII staining was seen only within vessels (magnification, 100×).