Variation of spermatogenic and Sertoli cell number detected by fine needle aspiration cytology (FNAC) in Iberian red deer during and out of the breeding season.

The aim of the present study was to evaluate spermatogenesis in Iberian red deer, a short-day seasonal breeder, using the fine needle aspiration cytology (FNAC) technique. Reports on spermatogenesis in deer are limited and here, for the first time, FNAC has been used to evaluate changes in such physiological process during and out of the breeding season. Testes were collected from 51 stags from November 2010 to February 2011. The Sertoli index and spermatic index were significantly higher during the breeding season than out of the breeding season (P=0.0477 and P=0.0125, respectively). A similar pattern was described by histological analysis, in which both Sertoli cell number per tubular cross-section and Johnsen score decreased significantly from the breeding season to the non-breeding season (P=0.0131 and P=0.0010, respectively). Data provided by FNAC were correlated with histology: the Sertoli index was positively correlated with Sertoli cell number per tubular cross-section (P=0.0015), whereas the spermatic index was correlated with the Johnsen score (P=0.0497). The results of the present study indicate that FNAC is a reliable technique to evaluate spermatogenesis in Iberian red deer and suggest that Sertoli cell number is not stable in these species, reaching highest values during the breeding season.