Frozen media preserves blastocyst development and quality in cattle embryos produced in vitro: a six-month evaluation

Media preparation represents a critical source of variability in cattle in vitro embryo production (IVP), with batch-to-batch inconsistencies potentially affecting experimental outcomes. This study evaluated whether cryopreservation of IVP media could maintain embryonic developmental competence while reducing preparation-related variability. We compared the efficacy of frozen (-80 °C) versus freshly prepared synthetic oviduct fluid (SOF)-based media for producing cattle blastocysts over storage periods of one, three, and six months. Approximately 400 cumulus-oocyte complexes were allocated to each of the two replicates carried out for each month tested. We tested five groups: frozen medium containing 4-(2-Hydroxyethyl)piperazine-1-ethanesulfonic acid (HEPES), frozen fertilization medium, frozen culture medium, all frozen media, or fresh media control. Development parameters included cleavage rates at 48 h post-fertilization, blastocyst formation at 168 and 192 h, and hatching rates at 192 h. Cell counts were assessed via immunocytochemistry for trophectoderm (CDX2+) and epiblast (SOX2+) lineages. Although frozen media exhibited increased pH values compared to fresh preparations, no statistically significant differences were observed in cleavage rates, blastocyst development, or hatching rates between frozen and fresh media groups. Trophectoderm and epiblast cell numbers remained comparable across all treatment groups, indicating preserved cell differentiation and allocation. These findings demonstrate that cryopreservation of IVP media maintains embryonic developmental competence equivalent to freshly prepared media. Implementation of frozen media protocols offers substantial practical advantages, including reduced batch variability, enhanced experimental consistency, and improved laboratory efficiency due to the preparation of larger quality-controlled media volumes for extended use.