Immunohistochemical staining of a fetal ovary specimen, gestation week 13. Hematoxylin-eosin (HE) staining (panels A, G, M) and immunohistochemical staining with mAbs MA454 (panels B, H, N), M3H67 (panels C, I, O), 57B (panels D, J, P), CT7-33 (panels E, K, Q), and ES121 (panels F, L, R) are shown. Undifferentiated ovarian tissue with dense accumulation of germ cells is seen upon hematoxylin-eosin staining (panels A, G, M). Intense immunostaining of focal germ cells is observed with mAbs M3H67 (panels C, I, O), 57B (panels D, J, P), and CT7-33 (panels E, K, Q). Single immunopositive cells are seen with mAbs MA454 (panels B, H, N) and ES121 (panels F, L, R). Objective magnification: 10x (panels A - F), 20x (panels G - L), 40x (panels M - R).