In vitro development of day 2 embryos obtained from young, fertile mares and aged, subfertile mares.

The research focuses on comparing the development of early-stage embryos from young, fertile mares and aged, subfertile mares. The embryos were co-cultured with oviductal epithelial cells from both age groups, manifesting similar development rates, but the blastocysts from aged mares appeared inferior in various aspects.

Objective of the Research

• This study aims to investigate the development of day-2 embryos obtained from young fertile mares and aged subfertile mares. The investigation also evaluates how these embryos develop when co-cultured with oviductal epithelial cells procured from utilized mares. The embryo and epithelial cell donors varied in their age and fertility condition.

Methodology Employed

• The researchers leveraged a 2 x 2 crossover design for the study. The embryo and oviductal epithelial cell donors were young, fertile mares aged between 2 and 7 years old, and aged, subfertile mares aged between 17 and 24 years old.
• The embryos were collected from the oviducts two days post ovulation and were paired, with embryos procured from young mares grouped with embryos taken from aged ones. Eight pairs of these embryos were co-cultured on young mare oviductal epithelial cells, and another eight pairs were co-cultured on aged mare oviductal epithelial cells.
• A group of five additional embryos obtained from young mares were co-cultured with oviductal epithelial cells from either young or aged mares but were not paired.
• Co-culturing lasted for seven days at a temperature of 38.5 degrees Celsius in a 5% CO2 environment or until morphological degeneration was observed.

Research Findings

• The researchers found that the proportions of paired embryos that matured to the blastocyst stage did not show a significant difference for embryos sourced from both young and aged mares when co-cultured with either young or aged mare oviductal epithelial cells.
• However, despite the overall development rate of embryos to the blastocyst stage being similar between the two groups, it was observed that blastocysts derived from embryos obtained from aged mares were inferior in certain parameters, such as the number of cell nuclei, quality score, and diameter at day 7, when compared to blastocysts obtained from young mares.