Abstract
An inhibiting factor of compensatory ovarian hypertrophy has recently been found in the non-dialyzable fraction of bovine follicular fluid1). In the present experiment, partial purification of this inhibiting factor was undertaken by the following methods; salting out by ammonium sulfate and fractionation on a column of Sephadex G-200. Follicular fluid was recovered from the ovaries of cows obtained at slaughterhouse and activity of the inhibiting factor was evaluated using mice by (i) suppression of compensatory ovarian hypertrophy, and by (ii) the decrease of the number of ova ovulating and suppression of the increase of uterine weights induced by PMSG and HCG. The results obtained were as follows. 1) The number of ova ovulating and the increase of uterine weights induced by the treatment with PMSG and HCG was decreased or suppressed in mice which were received the non-dialyzable fraction of follicular fluid recovered from medium- and large-sized follicles. Inhibiting activity of the non-dialyzable fraction of follicular fluid was decreased by incubation for 30 min at 56°C. 2) Selecting precipitation with ammonium sulfate was carried out on bovine follicular fluid to concentrate the inhibiting substance and most of the inhibiting substance was salted out at 14.5 to 18.5% ammonium sulfate. 3) The substance salted out at 14.5 to 18.5% ammonium sulfate was separated as two peaks on a column of Sephadex G-200, and the inhibiting substance was eluded as the second peak.
