Xenotransplante de tecido ovariano fetal bovino: vantagens e desafios para preservação da viabilidade do gameta e para incremento do ganho genético

Abstract

The use of foetal bovine ovaries tissue xenograft may allow optimization in utilization of genetic material of animals of high genetic merit even before birth, as in the case of cow death before the end of gestation. By using this tissue, good follicular viability results are expected, since at this stage, the ovaries have a greater reserve of primordial follicles, which are even more tolerant to cryopreservation biotechnologies, such as vitrification. Given the applicability of vitrification and xenotransplantation as methods of preserving the reproductive potential, it is important to study possible genetic alterations resulting from these techniques. The objective of the first article was to evaluate, after in vitro an in vivo (xenograft) culture of foetal bovine ovarie tissue, the morphology and developmental capacity of the preantral follicles, as well as the oxidative stress and the levels of Cell degeneration and tissue apoptosis; and in the second article, to evaluate after vitrification and/or xenograft of foetal bovine ovarie tissue morphological chromosomal changes in tissue cells, in addition to the morphology and developmental capacity of preantral follicles. In vivo cultivation groups (xenograft) were effective in maintaining follicular viability, stimulated moderate follicular development and reduced levels of cells degeneration and reactive oxygen species compared to those in the fresh control group. Tissue recovered after 14 days had higher morphology, adherence, and hemorrhage scores than those undergoing recovery after 7 days. The recovery of fragments after 14 days xenotransplanted, has good results in maintaining the viability of preantral follicles included in bovine fetal ovarian tissue, and provides support for follicular growth. Fragments submitted to vitrification and/or xenotransplantation showed an increase in the number of cells with micronuclei, compared to the fresh control group. The morphology, adherence, and hemorrhage scores between fragments submitted to fresh xenograft and those submitted to vitrification prior to xenograft were similar. Follicular reserve was maintained, however, xenotransplantation and vitrification are able to generate structure DNA damages in the ovarian tissue cells of bovine fetuses.