Human oocyte vitrification: the permeability of metaphase II oocytes to water and ethylene glycol and the appliance toward vitrification.

Objective: To determine the permeability of human metaphase II oocytes to ethylene glycol and water in the presence of ethylene glycol, and to use this information to develop a method to vitrify human oocytes.

Design: An incomplete randomized block design.

Setting: A university-affiliated assisted reproductive center.

Patient(s): Women undergoing assisted reproduction in the Center for Reproductive Medicine at Shandong University.

Intervention(s): Oocytes were exposed to 1.0 molar ethylene glycol in a single step and photographed during subsequent volume excursions.

Main Outcome Measure(s): A two-parameter model was employed to estimate the permeability to water and ethylene glycol.

Result(s): Water permeability ranged from 0.15 to 1.17 microm/(min.atm), and ethylene glycol permeability ranged from 1.5 to 30 microm/min between 7 degrees C at 36 degrees C. The activation energies for water and ethylene glycol permeability were 14.42 Kcal/mol and 21.20 Kcal/mol, respectively.

Conclusion(s): Despite the lower permeability of human metaphase II oocytes to ethylene glycol compared with previously published values for propylene glycol and dimethylsulfoxide, methods to add and remove human oocytes with a vitrifiable concentration of ethylene glycol can be designed that prevent excessive osmotic stress and minimize exposure to high concentrations of this compound.