ИСТИНА

Vitrification of laser treated human blastocysts using reduced concentrations of permeable cryoprotectants was carried out by submerging cut standard straws (CSS) into liquid nitrogen. The CSS were made by cutting a standard 0.25 ml straw at an angle of ~45. After laser assisted hatching, 6 day blastocysts (n = 250) were loaded into droplets of ~0.75 ll in the CSS and were either plunged directly into liquid nitrogen or first encased in a standard 0.5 ml straw (aseptic technique) before being vitrified. Permeable cryoprotectants (ethylene glycol +Мe2SO) at concentrations of 15% and 20% v:v were tested for their effect on post warming re-expansion and post transfer pregnancy rates. Our results indicate that the use of reduced concentrations of cryoprotectants and aseptic packaging of blastocysts did not have any statistically significant impact on the study outcomes.