Ultrastructure of cryopreserved horse embryos.

This research article presents a study on the ultrastructure of cryopreserved horse embryos. It observes the impact of cryopreservation on the morphology and the microscopic structure of the embryos’ intracellular organelles.

Objective and Methodology

• The researchers aimed to identify the potential structural changes that might occur in horse embryos exposed to a cryoprotectant or cryopreservation, which may cause cellular death.
• For this purpose, 15 Quarter horse embryos were retrieved non-surgically about six days after ovulation.
• The complex method of electron microscopy was used in the study to obtain a detailed observation of the intricate structure of the intracellular organelles.

Findings

• The scientists observed that the horse embryos neither fully re-expanded in the 10% glycerol freezing medium, nor did they completely re-expand in the isotonic holding medium following the removal of glycerol. This observation held true regardless of whether or not the embryo had undergone freezing.
• The embryos were frozen using the same method which had previously led to a 30% pregnancy rate for similarly frozen embryos.
• Following the treatment, the junctional complexes between the trophoblast cells, plasma, and the nuclear membranes of the trophoblast and inner cell mass (ICM) cells remained intact.

Post-treatment Changes

• The research also identified changes in lipid droplets and some degree of mitochondrial degeneration in the ICM cells of the glycerol-treated embryos.
• Interestingly, the lipid change was not observed in the embryos that were frozen and then thawed. Though, mitochondrial alterations were evident in both the trophoblast and ICM cells, with extensive damage noted in the latter.