ABSTRACT
Since the first report in 1972 of cryopreservation of mammalian embryos resulting in the birth of live mice offspring, attempts to cryopreserve human oocytes, similar to the results with oocytes of domestic animals, mostly failed for many years. Ultra-rapid vitrification has been used successfully to cryopreserve oocytes and embryos from a wide variety of mammalian species, and has resulted in a considerable increase in the overall efficiency of cryopreservation of human oocytes and embryos. In the same year, Kuwayama also obtained the first success of human oocytes vitrification using the ultra-rapid method with an acceptable high survival rate. Regarding VS, there was still lower viscosity of the solutions, difficulty judging completion of the oocyte in VS equilibration, difficulty loading oocytes on vitrification container sheets within a limited time, and stickiness of oocytes to the sheet at warming in thawing solution.
