Growing cattle embryos beyond Day 8-An investigation of media components

The growth of viable cattle embryos in culture to stages beyond the hatching blastocyst is of interest to developmental biologists wishing to understand developmental events beyond the first lineage decision, as well as for commercial applications, because a lengthening of the culturing time allows more time for diagnostic tests on biopsies, whereas extended survival can be used as a better assay system for monitoring developmental potential. We here report on a novel extended culture medium for embryo growth until embryonic day (Day) 12. We used a non-invasive morphological characterisation system that scored viability, inner cell mass (ICM) grade, hatching and embryo and ICM diameter. The basal medium was based on published uterine fluid concentrations of amino acids, carbohydrates and electrolytes. Addition of fetal bovine serum was necessary and the additive ITSX greatly improved culture success. We tested the inclusion of a seven-growth factor cocktail consisting of Activin A, Artemin, BMP4, EGF, FGF4, GM-CSF/CSF2 and LIF, as well as omission of individual components of the cocktail. In the context of the growth factor cocktail, Artemin and BMP4 provided the greatest benefit, while FGF omission had more positive than negative effects on embryo characteristics. Lastly, replacement of ITSX by B27-additive led to the most successful culture of embryos, in all media permutations. (C) 2020 Elsevier Inc. All rights reserved.

Automated summary

A novel extended culture medium for cattle embryos was developed, allowing growth until embryonic day 12. The inclusion of specific growth factors and additives significantly improved culture success, with Artemin and BMP4 providing the greatest benefit. Replacement of ITSX with B27 led to the most successful embryo culture.