Figure 1

Characterization of the Acr-EGFP rat testis tissue. (a) The Acr-EGFP rat testis at postnatal days 15 (P15), P18, and P42 in brightfield (BF) and under GFP-excitation (GFP). GFP fluorescence was observed faintly on P15 and clearly on P18. Insets provide magnified views showing green fluorescence dot scattering on P15 and lining along the seminiferous tubules on P18. On P42, the GFP fluorescence grew stronger. (b) Seminiferous tubules of a 56 dpp rat showing strong GFP fluorescence. On closer observation with a stereomicroscope, the seminiferous tubules showed aligned strong GFP dots throughout the circumference of the tubule cylinder. (c) Released spermatids and spermatozoa showed GFP-positive acrosomes. (d) Immunohistochemistry of the testis tissue with antibodies to GFP and γH2AX along with Hoechst nuclear staining demonstrated that cells whose entire nuclei were yH2AX-positive, i.e., lepto-zygotene spermatocytes, were GFP-negative (white arrow), while the γH2AX-specked positive cells, i.e., pachytene spermatocytes, were GFP-positive (white arrowhead). In the center of the tubules, strong GFP aggregation in the acrosome was observed (yellow arrowheads). The rectangular areas in the upper panels are enlarged in the bottom panels. Scale bars: 2 mm (a), 1 mm (b top), 200 μm (b bottom), 20 μm (c), 50 μm (d top), 10 µm (d bottom).