This study investigates the immunolabeling of key iron-related proteins (Transferrin Receptor 1, Transferrin Receptor 2, and Ferritin Heavy chain 1) and Proliferating Cell Nuclear Antigen (PCNA) in canine SCO tubules within distinct microenvironments: seminomas, Sertoli cell tumors, and isolated. The gene discussed is TFRC; the disease is Sertoli cell tumor.