After euthanasia, testicles were obtained, tunica albuginea was removed with sterile forceps,\u00a0and seminiferous tubules were treated with collagenase for 10 minutes at 37\u00b0C (5 mg\/ml of\u00a0collagenase, SIGMA C5138). Using a trans-illumination method, cycles of spermatogenesis\u00a0were detected. Sections of seminiferous tubules, developing the Golgi-acrosome complex\u00a0in stages VI to VIII, were selected and cut under stereoscope. The tubules were placed on\u00a0slides containing 40 \u03bcl PBS and extruded with a cover-slip in order to obtain the spermatogenic\u00a0cells. Spermatogenic cells were fixed and smeared on slides or transferred to microtubes.