Viability of equine embryos after puncture of the capsule and biopsy for preimplantation genetic diagnosis.

This research investigates the impact of penetrating the capsule of an equine embryo for genetic analysis, looking to see if this process affects the embryo’s viability. Results indicate that blasting the capsule doesn’t cause harm, as pregnancy rates remained high after the procedure, foals were born healthy, and genetic information could be effectively collected and analyzed.

Research Methodology

• The study focused on the resilience of the capsule (or zona pellucida) that engulfs equine embryos. Samples were taken from early and expanded blastocyst stages.
• A Piezo drill was used to puncture the capsule and take biopsy samples from the trophoblast (the outer layer of the embryo that provides nutrients to the developing cells).
• The samples were gathered immediately or after being transported overnight in warm conditions. This procedure was done on day 6, 7, and 8 embryos.

Findings

• Equine embryos could survive after their capsules had been breached. The pregnancy rates after performing this procedure varied from 100% (Day-6 immediately sampled) to 67% (Day-6 shipped overnight).
• Encapsulated Day-7 and Day-8 embryos showed high pregnancy rates both for immediately and overnight sampled ones. 50% of the larger Day-8 embryos established pregnancies after biopsy.
• Normal pregnancies and healthy foals were reported in all nine mares that were allowed to carry their pregnancy to term.

DNA Analysis

• Biopsied cells from the eight embryos that produced foals were subjected further to a whole genome amplification. Sex was successfully determined from the amplified DNA in all samples.
• Identification of disease-causing mutations matched the analyses for two specific genes in the embryo-foal pair samples. This process confirmed the genetic consistency between the biopsied embryo and the resultant foal.

Implications

• Results suggest that equine embryos can survive even after their capsules have been breached for genetic analysis, implying the potential for embryos to be studied, manipulated, or preserved without risking their viability.
• However, the study notes that further research is necessary to determine whether the breach caused by this procedure is only temporary or a more enduring one. This information is crucial in shaping how embryos are handled, especially in terms of long-term preservation.