The objective of this experiment was to determine the efficiency and the effect of different enzymatic digestion periods on the number and developmental stages of preantral follicles isolated from bovine fetal ovaries. The presence of basal membrane, surrounding granulosa cells-oocyte complex, was observed, after digestion, through histologycal study. For this, ovaries from bovine fetues, were collected in slaughterhouses, between 150 and 270 days of pregnancy. In the laboratory, the ovaries were cut into several fragments with surgical scissors and dissociated with Pasteur pipette, having either 1000 or 500mum diameter. After these steps, the fragments were submitted to an enzymatic digestion with collagenase in a concentration of 200IU/ml of modified TCM 199, for periods of 20, 30 or 40 minutes. The results showed that determined the total number and the quantity of the different developmental stages of isolated preantral follicles were similar in the three different periods of enzymatic digestion. The histological analyses demonstrated that the enzymatic digestion periods did not affect the morphological structure of the follicles.
preantral follicles; bovine; in vitro culture
