Ovarian tissue cryopreservation is an important method of female fertility preservation

slow freezing of ovarian tissue has poor follicular survival and low retransplantation efficency. In this paper

the ovarian tissue cooling procedure was optimized by ice seeding

and the effects of ice seeding temperature and cooling rate after seeding on the ovarian tissue cryopreservation effect were analyzed. The programmed cooling apparatus was combined with an ultrasonic device to achieve ultrasonic seeding of ice crystals

and ultrasonic intensity was screened. Ovarian survival and histology were assessed after rewarming. The results showed that the optimized cooling procedure with ice seeding reduced the damage to ovarian tissues。When ice seeding was triggered at -11°C with a cooling rate of 1°C/min after nucleation

follicle survival was 88.02%. Ultrasonic nucleation equipment allowed contactless ice seeding of the samples

which reduced the risk of contamination and improved the success rate of ice seeding

and the follicle survival rate of frozen ovarian tissue increased to 88.38%. The optimization of the procedure as well as the improvement of the equipment improved the effect of ovarian tissue cryopreservation

reduced the risk of introducing contamination during the cryopreservation process

and provided a new method for the slow cryopreservation of ovarian tissues in the clinic.