02843naa a2200349 a 450000100080000000500110000800800410001902200140006010000190007424501550009326000090024830000150025752018460027265000240211865000130214265300210215565300200217665300190219665300150221565300190223070000240224970000180227370000190229170000200231070000190233070000190234970000170236870000200238570000200240570000210242577300470244621279862020-12-11       2021    bl uuuu     u00u1 u    #d  a0093-691X1 aMARQUES, T. C.  aBlastocoel fluid removal and melatonin supplementation in the culture medium improve the viability of vitrified bovine embryos.h[electronic resource]  c2021  ap. 134-141  aIn this study, we investigated the effects of melatonin supplementation in the culture medium and blastocoel fluid removal (BFR) before vitrification on the quality and viability of in vitro-derived bovine embryos. After fertilization, presumptive zygotes were assigned to one of the following treatments: control, in vitro standard culture (IVC) medium; IVC þ M109 , IVC medium supplemented 109 M melatonin; or IVC þ M109 BFR, IVC medium supplemented with 109 M melatonin plus BFR on day 7 (D7) of culture. D7 blastocysts were vitrified by the Cryotop method and, after 5 mo of storage, were warmed and incubated for an additional 72 h. The re-expansion rate was evaluated after 2 and 24 h, and the hatching rate was evaluated after 24, 48, and 72 h. At 72 h, the total number of cells (TNC); number of apoptotic cells (NAC); and expression of genes related to oxidative stress (HSPA5), cell metabolism (SLC2A3), cell repair (MSH6), placentation (KRT8 and PLAC8), and implantation (FOSL1) were assessed in the blastocysts. Less than 30% of the control blastocysts re-expanded until 2 h, whereas more than 85% of the IVC þ M109 and IVC þ M109 BFR blastocysts re-expanded (P &lt 0.05). The hatching rate of IVC þ M109 BFR blastocysts increased at all time points (P &lt 0.05), reaching 66.8% at 72 h of incubation. The TNC was similar among treatments (P &gt 0.05), regardless of vitrification/warming and re-cultivation. The NAC:TNC was smaller for melatonin-treated blastocysts (P &lt 0.05). BFR increased HSPA5 (P ¼ 0.0118) expression and did not affect SLC2A3, MSH6, KRT8, and FOSL1 expression (P &gt 0.05). In conclusion, melatonin (109 M) supplementation in the culture medium and BFR on D7 of culture increased the hatching rate 24, 48, and 72 h after warming of the vitrified embryos, indicating an improvement in cryotolerance.  aCultura de Embrião  aEmbrião  aApoptose celular  aCriotolerância  aFertilização  aMelatonina  aVitrificação1 aSANTOS, E. C. da S.1 aDIESEL, T. O.1 aMARTINS, C. F.1 aCUMPA, H. C. B.1 aLEME, L. de O.1 aDODE, M. A. N.1 aALVES, B. G.1 aCOSTA, F. P. H.1 aOLIVEIRA, E. B.1 aGAMBARINI, M. L.  tTheriogenology, Vv. 160, p. 134-141, 2021.