Cryopreservation of whole bovine ovaries: comparisons of different thawing protocols

ObjectiveThe aim of this study was to perform a comparative investigation of several different thawing protocols and to determine an appropriate protocol for thawing whole bovine frozen ovaries.Study designBovine ovaries were slowly frozen and then thawed by applying different protocols. Ultrastructural change, follicle viability, and the hormone levels of culture supernatant were measured.ResultsThe percentage of morphologically normal primordial follicles and the hormone levels of culture supernatant in group D (two-step, thawing in water at 39 °C) were significantly higher than those in any other group. Moreover, the ultrastructural alteration of oocyte in group D (two-step, thawing in water at 39 °C) was slighter than those in any other group.ConclusionsThe two-step protocol involving short-term exposure to water at a moderately high temperature (39 °C) proved to be a suitable for thawing bovine whole ovaries.