Objective - To evaluate the effect of dynamized follicle-stimulating hormone (FSH) on the survival, activation and growth of ovine preantral follicles (PFs) in vitro.Methods - Ovarian fragments were cultured for 1 or 7 days in alpha minimum essential medium (α-MEM+) control in the absence or presence of alcohol (Al control) or FSH (6cH, 12cH and 30cH) added at intervals of 24 or 48 h. The ovarian fragments were processed, coded and analyzed by a blinded observer by classical histology (CH), fluorescence microscopy (FM) and transmission electron microscopy (TEM).Results - After 7 days of culture, the group which to which FSH 6cH was added at 24 h intervals showed better rates of follicle survival and activation compared to α-MEM+ control or Al control (p < 0.05). This group also showed higher follicle and oocyte growth than α-MEM+ control (p < 0.05). FM and TEM techniques confirmed that FSH 6cH promoted viability and ultrastructural integrity of follicles after 7 days of culture.Conclusions - FSH 6cH (24 h) treatment maintained the viability, and promoted the activation and in vitro growth of ovine PFs.