Figure 5. Immunohistochemical staining on the serial paraffin sections of rat testis for Smad2 (left column) and Smad3 (right column). The positive signal for Smad2 and Smad3 is brown. Ten days of age (A and B), 25 days of age (C and D), and 60 days of age (E–J). Panels (A–F) are 200x magnification, (G–J) are 400x magnification. Roman numerals represent the stage of seminiferous epithelium. Lc indicates Leydig cells; Sc, cytoplasm of Sertoli cell staining; Sn, nucleus of Sertoli cell staining; SG, spermatogonia; L-Z, leptotene-zygotene spermatocytes.