Photomicrographs of seminiferous tubules of rats from C-30 (A), T-30 (B-D) and T-60 (E-G) submitted to the TUNEL-method. (A) TUNEL-positive germ cell is observed in the epithelium (arrow). (B-D) Primary spermatocytes (thick arrows), spermatogonia (thin arrows) and elongate spermatids (arrowheads) are labeled by TUNEL method. (E-G) Spermatogonia (thin arrows), primary spermatocytes in different stages (thick arrows) and round spermatids (arrowheads) are TUNEL-positive. A giant multinucleated cell derivative from round spermatids (white arrow) is also positive. Fig. 3A: ×260; Figs. 3B-3G: ×710.