Hatchability evaluation of bovine IVF embryos using OCT-based 3D image analysis

Area of Science:

• Reproductive biology
• Biotechnology
• Veterinary medicine

Background:

• Embryo transfer in cattle often fails to establish pregnancy.
• Accurate evaluation of bovine embryo quality is crucial for successful in vitro fertilization (IVF) and transfer outcomes.
• Novel parameters are needed to improve bovine embryo assessment.

Purpose of the Study:

• To investigate the relationship between in vitro hatchability and morphological parameters of bovine embryos using optical coherence tomography (OCT).
• To identify new parameters for evaluating bovine embryo quality and predicting hatchability.
• To establish OCT as a tool for assessing structural data of blastocyst-stage embryos.

Main Methods:

• Bovine embryos from Japanese Black cattle were produced via IVF.
• Blastocyst quality was assessed using inverted microscopy (IETS Codes 1-3).
• Three-dimensional OCT imaging was performed on Day 7 post-IVF, followed by hatchability assessment on Day 9. 22 parameters were measured for 42 embryos.

Main Results:

• Hatched (H) embryos exhibited significantly lesser trophectoderm (TE) and TE+zona pellucida (ZP) thickness compared to non-hatched (NH) embryos.
• H embryos showed greater volumes of TE, ZP, blastocoel, and the whole embryo, along with a larger blastocoel diameter.
• Principal Component Analysis (PCA) indicated that increased blastocoel-related values and decreased TE/ZP thickness are indicators of hatchability.

Conclusions:

• OCT-derived structural parameters can serve as potential predictors of bovine IVF embryo quality and hatchability.
• Morphological features assessed by OCT, such as TE thickness and blastocoel volume, are linked to successful embryo development.
• This study supports the use of OCT imaging for non-invasive, quantitative evaluation of bovine embryos, potentially improving pregnancy rates.