ABSTRACT
Oocyte, embryo and ovarian tissue cryopreservation are being increasingly proposed for fertility preservation among cancer patients undergoing therapy to enable them to have babies after the cancer is cured. Embryo cryopreservation is not appropriate for single girls without any spermpartner. It is impossible in cases requiring immediate cancer cure because oocyte retrieval is an extended procedure. Thus ovarian tissue cryopreservation has been suggested for fertility preservation especially in cancer patients. The main goal of ovarian cryopreservation is re-implanting the tissue into the body to restore fertility and the hormonal cycle. Different cryopreservation protocols have been examined and established for vitrification of biological samples. We have used Cryopin to plunge ovarian tissue into the liquid nitrogen and promising results have been observed. The possibility of recurrence of malignancy in the reimplanted tissue could be a problem. Xenografting-implantation of the preserved tissue in another species-also has its drawbacks such as molecular signaling from the recipient. In vitro follicle culturing is a safer method to obtain mature oocytes for fertilization and the various studies that have been carried out in this area are reviewed in this paper
ABSTRACT
This study aimed to assess follicle survival after xenotransplantation of sheep ovarian tissue into male and female immunodeficient rats. We evaluated the effects of gonadotropin treatment on follicular development in the transplanted tissue. In this experimental study, sheep ovarian cortical strips were transplanted into the neck back muscles of 8 male and 8 female immunodeficient, castrated rats. Fourteen days after surgery, each rat was treated with human menopausal gonadotropin [hMG] for 9 weeks. One day after the last injection, ovarian tissues were removed and fixed for histology assessment. Histology analyses were performed before and after grafting. Estradiol [E[2]] levels were measured before and after gonadectomy, and at the end of the experiment. The control group consisted of 7 male and 7 female non-castrated/non-grafted rats and the sham group comprised 7 male and 7 female castrated/ non-grafted rats for comparison of serum E2 concentrations. The percentage of primordial follicles decreased after transplantation in male [25.97%] and female [24.14%] rats compared to the control group [ovarian tissue non-grafted; 37.51%]. Preantral follicles increased in the male [19.5%] and female [19.49%] transplanted rats compared to the control group [11.4%]. Differences in antral follicles between male [0.06 +/- 0.0%] and female [0.06 +/- 0.0%] rats were not noticeable compared to control [1.25 +/- 0.0%] rats. We observed a significantly higher percent of mean E[2] secretion in grafted males compared to grafted females [P<0.05]. Despite significant differences in E[2] secretion between xenografted male and female rats, we observed no statistical differences in terms of follicular development