PCNA ICC on testes of implanted frogs. Representative photomicrographs of PCNA ICC performed on testicular sections of frogs implanted with (A, D) Ch, (B, E) DHT, or (C, F) E2. (A, B, C) Testes from animals implanted for 10 days. (D, E, F) Testes from animals implanted for 30 days. Brown stain = PCNA immunoreactivity. Blue stain = hematoxylin counterstain. Red arrow = I SPG; dark blue arrow = II SPG; light blue arrow = I SPC. Note DHT and E2 had no visible effects on testes of animals implanted for 10 days (A, B, C). In contrast, DHT and E2 visibly reduced the presence of PCNA-positive germ cells in animals implanted for 30 days (D, E, F). Σχαλεβαρ = 100 μm.