Progesterone Receptor (PGR) is not Required for Bovine Hypoblast Migration and Embryonic Disc Formation in vitro

Galiano-Cogolludo B., Hamze J. G., Lamas-Toranzo I., Pérez-Gómez A., González-Brusi L., Tüten Sevim E., ...More

19th International Congress on Animal Reproduction, Bologna, Italy, 26 - 30 June 2022, pp.177

  • Publication Type: Conference Paper / Summary Text
  • City: Bologna
  • Country: Italy
  • Page Numbers: pp.177
  • Akdeniz University Affiliated: Yes



Progesterone has been positively associated with conceptus length and embryo survival in cattle. However, it is unclear whether this positive effect is exerted through a direct effect upon the embryo or indirectly, by promoting changes in uterine fluid composition. While progesterone supplementation to conventional embryo culture up to Day 8 (D8) is not required for embryo development, post-hatching embryo culture (D8 to D12) requires the addition of multi-compound supplements containing progesterone. The objective of this study was to determine the developmental effects of progesterone receptor (PGR) ablation.



In vitro matured bovine oocytes were injected with mRNA encoding for Cas9 alone (control group, C) or combined with sgRNA against PGR (C+G group). Following fertilization and culture, blastocysts were cultured in a post-hatching system up to D12. At D12, embryos were fixed and epiblast and hypoblast development were analyzed by

immunocytochemistry for SOX2 and SOX17, respectively. Following individualized image analysis, samples were recovered and genotyped by miSeq to determine which

embryos in C+G group were KO.



PGR ablation did not impair blastocyst formation, as similar developmental rates were obtained in C or C+G groups (33.4±2.6 vs. 26.7±4.3 %, mean±s.e.m. for C and C+G,

respectively, t-test p>0.05). In vitro development from D7 to D12 was also similar between groups (85.4±5.7 vs. 81.3±6.3, mean±s.e.m. for C and C+G, respectively, t-test p>0.05). 22 out of 45 D12 embryos analyzed in C+G group were KO. D12 embryo diameter was not affected by embryo genotype (772±74 vs. 648±64 vs. 731±44 μm, mean±s.e.m. for WT, edited non-KO and KO, respectively, ANOVA p>0.05). The proportion of embryos showing complete hypoblast migration was similar in WT (23/32, 72 %), edited non-KO (12/20, 60 %) and KO (19/22, 86 %) embryos (Chisquare p<0.05). Epiblast survival (SOX2+ cells) rates were also similar in WT (26/32, 81 %), edited non-KO (9/20, 45 %, 60 %) and KO (12/20, 60 %) and no differences were noted on embryonic disc (ED) formation rate (20/32 63 % vs. 6/20 30 % vs. 10/22 45 % for WT, edited non-KO and KO, respectively Chi-square p>0.05).



Direct progesterone signaling to the embryo through PGR is not required for hypoblast migration and ED formation.