Satosi Kagabu1, Motoaki Umezu2. 1. Faculty of Agriculture, Yamaguchi University, Yamaguchi, and. 2. Faculty of Agriculture, Utsunomiya University, Utsunomiya, Japan.
Abstract
Background and Aims: Following unilateral ovariectomy, the contralateral ovary underwent hypertrophy and the number of ovulations remained unchanged. The aim of the present study was to elucidate the mechanism, which occurred by this compensation, through examination of ovarian follicular development in operated rats. Methods: Rats were examined 1-8 weeks post unilateral operation. The ovaries were serially sectioned. All sections were examined and the size of each follicle was measured. Results: Large follicles soon recovered after surgery, but it took 5 weeks for small and medium-sized follicles to recover. The rate of atresia at the 'critical point' was 31.1% in unilateral ovariectomized animals and 73.9% in the sham-operated rats. Conclusions: These findings showed that in operated rats, the recovery of the number of follicles varied depending on the size of the follicle. Compared with the control animals, approximately twice as many large healthy follicles were saved from atresia at the 'critical point', producing a compensatory increase in the ovulation number (P < 0.01). (Reprod Med Biol 2005; 4: 89-93).
Background and Aims: Following unilateral ovariectomy, the contralateral ovary underwent hypertrophy and the number of ovulations remained unchanged. The aim of the present study was to elucidate the mechanism, which occurred by this compensation, through examination of ovarian follicular development in operated rats. Methods:Rats were examined 1-8 weeks post unilateral operation. The ovaries were serially sectioned. All sections were examined and the size of each follicle was measured. Results: Large follicles soon recovered after surgery, but it took 5 weeks for small and medium-sized follicles to recover. The rate of atresia at the 'critical point' was 31.1% in unilateral ovariectomized animals and 73.9% in the sham-operated rats. Conclusions: These findings showed that in operated rats, the recovery of the number of follicles varied depending on the size of the follicle. Compared with the control animals, approximately twice as many large healthy follicles were saved from atresia at the 'critical point', producing a compensatory increase in the ovulation number (P < 0.01). (Reprod Med Biol 2005; 4: 89-93).