Influence of hormone environment and donor age on cryopreserved common wombat (Vombatus ursinus) ovarian tissue xenografted into nude mice.

Developmentally competent oocytes can be collected from xenografted ovarian tissues; however, optimal xenograft conditions need to be established for this technique to be of use in assisted reproduction. In the present study, common wombat ovarian tissue was xenografted under the kidney capsule of nude mice to clarify the role of recipient gonadal status and donor tissue age on graft establishment, follicle development and oocyte recovery. Eighty-nine per cent of all grafts were recovered; of these, 78% contained growing follicles. In female graft recipients, follicle development to the antral stage occurred earlier in ovariectomised recipients compared with intact graft recipients. Similarly, follicle development occurred earlier in recipients of pouch young ovarian tissue grafts when compared with subadult xenografts. Follicle development proceeded to the antral stage in subadult grafts placed under the kidney capsule of male recipient mice, albeit at a slower rate than subadult grafts placed in female recipients. Oocytes were collected from grafts placed in female and male recipients, but no mature oocytes were observed at the time of collection, nor could these oocytes be matured in vitro. The present study demonstrated that common wombat pouch young tissue xenografted to female recipient mice, and subadult ovarian tissue xenografted to male recipient mice, can develop to the antral stage and can therefore facilitate oocyte collection. However, mature oocytes were not obtained using the current protocol.