Fluorescein Diacetate Assessment of Embryo Viability After Ultrarapid Freezing of Human Multipronucleate Embryos

Objective: To assess embryo viability after ultrarapid freezing-thawing.

Design: We studied the fluorescence pattern of 35 ultrarapidly frozen-thawed multipronucleate human embryos exposed to fluorescein diacetate.

Setting: All the embryos were obtained from the Medical Center for Fertility Diagnostics and In Vitro Fertilization and Embryo Transfer at Leuven (Belgium), a private care center.

Patients, Participants: None.

Interventions: None.

Main Outcome Measure: The fluorescence pattern was evaluated at room temperature after a 1-minute incubation in fluorescein diacetate solution, 4 hours and 24 hours after thawing.

Results: Healthy human multipronucleate embryos, when exposed to fluorescein diacetate, accumulated intracellular fluorescein and fluoresced brightly under ultraviolet light. On the other hand, embryos presenting submicroscopic cell membranes damage caused by different processes (e.g., high or low temperatures) lost the ability to accumulate intracellular fluorescein. All the ultrarapidly frozen embryos with normal looking blastomeres fluoresced brightly after a short exposure to fluorescein diacetate.

Conclusions: Our experiments indicate an intact cell membrane permeability and an integrity of the intracytoplasmatic esterase enzyme activity of human embryos ultrarapidly frozen.