56 Morphokinetic variability of bovine blastocysts in repeated ovum pickup-IVF production

A. de Paula Reis; D. Le Bourhis; S. Lancelin; H. Raoul; V. Cotil; L. Le Berre; G. Crozet; A. Trubuil; V. Duranthon; P. Salvetti

doi:10.1071/RDv36n2Ab56

RESEARCH ARTICLE

56 Morphokinetic variability of bovine blastocysts in repeated ovum pickup-IVF production

A. de Paula Reis ^A ^B , D. Le Bourhis ^C , S. Lancelin ^C , H. Raoul ^B , V. Cotil ^B , L. Le Berre ^C , G. Crozet ^B , A. Trubuil ^D , V. Duranthon ^A and P. Salvetti ^C

+ Author Affiliations

- Author Affiliations

^A Université Paris-Saclay, UVSQ, INRAE, BREED, Jouy-en-Josas, France,

^B Ecole nationale vétérinaire d’Alfort, Maisons Alfort, France,

^C Eliance, Paris, France,

^D Université Paris-Saclay, INRAE, MaIAGE, Jouy-en-Josas, France

Reproduction, Fertility and Development 36(2) 179-180 https://doi.org/10.1071/RDv36n2Ab56

A recent morphokinetic classification (Reis et al., 2018 Proc. of the 34th Annual Meeting A.E.T.E, Nantes) allows discrimination of in vitro produced bovine blastocysts with different levels of morpokinetic alterations: very low (EHB: early hatching blastocyst and HB: hatching blastocyst), intermediary: (DB: delayed blastocyst) or high (AB: arrythmic blastocyst). Embryos from these morphokinetic categories present differences on cryotolerance and embryonic genome activation (EGA). The current study is a retrospective assessment of the morphokinetic classification of blastocysts produced from repeated ovum pickup (OPU)/IVF in our laboratory. Holstein heifers (n = 30) were subjected to oestrous synchronisation (ES) and follicle stimulation (FS) as described by Idrissi et al. (2021 Sci. Rep. 11, 11618). Briefly: ES using a progesterone releasing intravaginal device (Days −9 to −2; 1.55 g PRID Delta^®); Day −3: 0.5 mg of cloprostenol, IM (Estrumate^®). Day 0: reference heat. Day 8: dominant follicle ablation (DFA); Day 8 to 13: 1.55 g of PRID Delta^®; Day 10 to 12: FS with decreasing doses of FSH/LH (Stimufol^®); Day 13: OPU1. Between OPUs (14-day interval): the heifers were constantly under 1.55 g PRID Delta, renewed every week. DFA and FS were performed at Day 8 and Days 10 to 12, respectively. Grade 1 to 3 COCs (IETS classification) were in vitro matured, and fertilized with frozen semen (5 Holstein bulls). The presumed zygotes were cultured in vitro in SOF BSAaa + 1% oestrus cow serum (ECS) from 22 hpi until the expanded blastocyst stage (6 dpi or 7 dpi) in WOW dish in 5% CO₂, 5% O₂, 90% N₂ in humidified atmosphere. Videomicroscopic images were acquired every 15 min (Primo Vision^®). The blastocysts were classified into categories EHB, HB, DB, AB (Reis et al. 2018) based on 27 morphokinetic parameters. The blastocyst rate (BR) (blastocyst/presumed zygotes) and EHB + HB rate: ((EHB+HB)/total blastocysts) of OPU1, 2, 3, 4, 5 were compared using X². A total of 101 OPU-IVF sessions were performed. Presumed zygotes and resulting blastocysts EHB, HB, DB and AB were respectively: OPU1 (238; 25, 40, 24, 23); OPU2 (85; 0, 9, 4, 13); OPU3 (226; 3, 12, 9, 25); OPU4 (150; 10, 12, 14, 15), OPU5 (114; 3, 8, 8, 18). The BR of OPU1 (47.1%) was significantly higher (P < 0.05) than OPU2 (30.6%), OPU3 (21.7%), OPU4 (34.0%) and OPU5 (32.5%). The BR of OPU4 was significantly higher than OPU3. The EHB + HB rate of OPU1 (58.0%, 65/112) was significantly higher than OPU2 (34.6%, 9/26), OPU3 (30.6%, 15/49) and OPU5 (29.7%, 11/37) but not different from OPU4 (43.1%, 22/51). These results show that the morphokinetic profile of bovine blastocysts produced by OPU-IVF every 14 days was variable. The influencing factors remain to be understood. This morphokinetic classification of blastocysts (Reis et al. 2018 Proc. of the 34th Annual Meeting A.E.T.E, Nantes) could be a useful tool for studies of factors influencing the quality of IVP blastocysts.

This research was funded by APIS-GENE.