Possibilities of cattle ovarian tissue conservation: A mini-review

Abstract

Cryopreservation of ovaries, their surface tissues or ovarian follicles represents the main source of female gametes in the future. In case of serious damage to the animal (limb fractures and others), when it is necessary to slaughter the animal, the ovarian tissue, ovarian follicle or the entire ovary can be collected and frozen. After thawing, the biological material may be transplanted or cultured in vitro as a source of oocytes for in vitro fertilization and in vitro embryo production. Ovarian tissue can be cryopreserved in various forms, such as fragments, slices, hemi-ovaries or whole ovaries with a vascular pedicle for future vascular anastomosis. Whole ovaries tend to be more difficult to preserve due to their dense tissue structure, intricate vascular system and diversity of cell types, all of which results in poor heat transfer and uneven cooling rates. An alternative approach to harvesting and vitrifying oocytes would be to cryopreserve ovarian tissues instead of follicles. Dissection of the ovary into ovarian fragments followed by puncture of the follicles is considered an effective technique toobtain a high number of oocytes in excellent conditions. Therefore, attention must be given to preserving this yield of good oocytes. This method of ovarian tissue storage is very promising but insufficiently elaborated yet. Cryopreservation of ovarian surface tissues or ovarian follicles represents the future main source of female gametes. Last year, we have started investigations focusing on cryopreservation of ovarian fragments from Slovakian cattle breeds for the purposes of national gene bank of animal genetic resources.