AUTHOR=Aardema H. , Bertijn I. , van Tol HTA. , Rijneveld A. , Vernooij JCM. , Gadella B. M. , Vos PLAM 

TITLE=Fatty Acid Supplementation During in vitro Embryo Production Determines Cryosurvival Characteristics of Bovine Blastocysts

JOURNAL=Frontiers in Cell and Developmental Biology

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2022.837405

DOI=10.3389/fcell.2022.837405

ISSN=2296-634X

ABSTRACT=<p><italic>In vitro</italic> production (IVP) embryos have a reduced quality and poor cryotolerance in comparison to <italic>in vivo</italic> embryos. This study investigated whether free fatty acid (FFA) conditions, fatty acid free (FAF)- synthetic oviduct fluid (SOF) without or with 25 μM of saturated stearic (C<sub>18:0</sub>) or unsaturated oleic (C<sub>18:1</sub>) acid during the first 5 IVP days, relate to quality and cryosurvival of day 8 blastocysts. Apart from the blastocyst scores, both 1) number and size of lipid droplets of fresh blastocysts and 2) total number and apoptotic and necrotic cells, before and after freezing-thawing, were scored by confocal microscopy. Blastocyst rates were significantly lower in the FAF SOF condition in comparison to other groups. Interestingly, blastocysts originating from the C<sub>18:1</sub> group, with a significantly higher lipid content, and blastocysts from the FAF SOF group demonstrated a high cryosurvival rate (70.1 and 67.4%, respectively) comparable with <italic>in vivo</italic> blastocysts (68%), in contrast to the poor cryosurvival of C<sub>18:0</sub> exposed embryos (17.6%). In all freeze-thawed embryos the average amount of apoptotic and necrotic cells increased albeit that the C<sub>18:0</sub> condition rates were higher (43.2%) when compared to C<sub>18:1</sub> (26.0%) and FAF SOF conditions (26.5%). The current data show that FFA administered during early embryonic development significantly affect the cryotolerance of blastocysts.</p>