Figure 2.

 Different patterns of cancer/testis (CT) antigen expression in adult testis. Many CT‐X antigens are expressed as nuclear antigens in spermatogonia, including NXF2 (A), SAGE, and most melanoma antigen (MAGE‐A) antigens. An exception is CT47 (B), expressed as cytoplasmic antigens in spermatogonia. The third pattern is represented by CT45 (C), which shows strongest expression in the pre‐meiotic spermatocytes as nuclear antigens. The fourth pattern is observed in meiosis‐related CT antigens, which are expressed as nuclear antigens in cells undergoing meiosis, an example being CT46/HORMAD1 (D). THEG is the only antigen that shows the fifth pattern, being expressed as a cytoplasmic antigen in the post‐meiotic spermatids as a cytoplasmic antigen (E). The last pattern, expression in the most mature sperm cells, is seen in SPANX (F), COX6B2, etc.