%0 Journal Article
%T Factors affecting the outcome of human blastocyst vitrification
%A Amr A Kader
%A Audrey Choi
%A Yasser Orief
%A Ashok Agarwal
%J Reproductive Biology and Endocrinology
%D 2009
%I BioMed Central
%R 10.1186/1477-7827-7-99
%X With the refinement of extended culture systems, it is becoming more reliable to obtain blastocysts in vitro [1]. Due their high implantation rates, it is becoming a common practice to limit transfer to one or two blastocysts at a time. Therefore, surplus blastocysts require an efficient cryopreservation method [2,3]. Slow freezing was the main method of cryopreservation [4], but vitrification is now on the rise. Vitrification is the glass-like solidification of a solution at a low temperature without ice crystal formation, which is made possible by extreme elevation in viscosity during freezing. This can be achieved by increasing the freezing and warming rates and/or increasing the concentration of the cryoprotectants [5]. Unlike slow freezing, vitrification results in the total elimination of ice crystal formation, both within the cells being vitrified and outside the cells in the surrounding solution [6]. Although high concentrations of cryoprotectants can be toxic, and the vitrified solution is prone to glass fractures, these effects can be controlled by adjusting the vitrification protocol and technique. With vitrification, the blastocyst is combined with cryoprotectants that maximize cytoplasmic viscosity while exerting a strong dehydrating effect. Vitrification is more convenient and is possibly superior because it avoids ice crystal formation. Over the last decade, vitrification techniques have been standardized, tested and improved via controlled experiments designed to elucidate the optimal conditions under which vitrification should be performed. This review will discuss the most commonly used loading devices, vitrification safety in terms of perinatal outcomes, and the factors that can affect the success of human blastocyst vitrification.During vitrification, the blastocyst is placed in a loading device surrounded by vitrification media. The device is then placed into liquid nitrogen, where it is stored. There are a variety of loading devices available t
%U http://www.rbej.com/content/7/1/99