The Near Future of Vitrification of Oocytes and Embryos: Looking into Past Experience and Planning into the Future

Abstract

Currently vitrification is the method of choice for low-temperature preservation of oocytes and embryos. However, that was not the case until about 10 years ago when freezing methods were used relatively successfully for embryos and investigated (unsuccessfully) for oocyte preservation. In this paper we will review the history of oocyte and embryo cryopreservation and look into ways and methods for overcoming and improving the vitrification method since it suffers from inherent disadvantages since it is a cumbersome, time-consuming and costly procedure.

Keywords: Cryopreservation; Embryos; Oocytes; Vitrification.

Fig. 1

Illustration of the influence of sample volume, viscosity, and cooling rates on the vitrification of an oocyte. The sample's volume reduction reduces chances for ice nucleations to form and increases cooling rates, high viscosity prevents both the formation of ice nucleations and the advancement of ice crystals once formed thus preventing flushing, and the high cooling rates also decrease ice crystal growth. If these three parameters are not fulfilled, nucleation, crystallization, and flushing occur which results in cell death.