The principal variables of cryopreservation: solutions, temperatures, and rate changes  S.P. Leibo, Ph.D., Thomas B. Pool, Ph.D.  Fertility and Sterility  Volume 96, Issue 2, Pages 269-276 (August 2011) DOI: 10.1016/j.fertnstert.2011.06.065 Copyright © 2011 American Society for Reproductive Medicine Terms and Conditions

Figure 1 Micrographs of a mouse oocyte suspended in 1 M DMSO being cooled on a cryomicroscope stage at 1.2°C/min to the indicated subzero temperatures. After being cooled to −135°C, the oocyte was warmed at 10°C/min until it was thawed. Details of the procedure are described in Leibo et al. (24). Fertility and Sterility 2011 96, 269-276DOI: (10.1016/j.fertnstert.2011.06.065) Copyright © 2011 American Society for Reproductive Medicine Terms and Conditions

Figure 2 The volumetric response of human oocytes suspended in 1.5 M solutions of ethylene glycol or of glycerol at 20°C. Part (A) shows data for times of 30 minutes; and part (B) shows data for times of 50 minutes. Oocytes that had failed to become fertilized were suspended in each solution, photographed, their cross-sectional areas measured, and their volumes calculated. The volumes are given as a percentage of the original volume of the oocytes in phosphate-buffered saline. Details of the procedure are described in McWilliams et al. (56). Fertility and Sterility 2011 96, 269-276DOI: (10.1016/j.fertnstert.2011.06.065) Copyright © 2011 American Society for Reproductive Medicine Terms and Conditions

Figure 3 Immunofluorescent micrographs of human oocytes that were cooled directly from 35 to 0°C for the indicated times. After being cooled, each oocyte was warmed rapidly to 37°C and then fixed and stained for immunofluorescence. The details of the procedure are described in Zenzes et al. (61). The photographs are reproduced from that paper and are reprinted with permission of the publisher. Fertility and Sterility 2011 96, 269-276DOI: (10.1016/j.fertnstert.2011.06.065) Copyright © 2011 American Society for Reproductive Medicine Terms and Conditions

Figure 4 Morphological survival of mouse oocytes cooled at each of the indicated rates and then warmed at various rates. The data are those of Seki and Mazur and are redrawn from that article. Details of the procedure are described in Seki and Mazur (47). Fertility and Sterility 2011 96, 269-276DOI: (10.1016/j.fertnstert.2011.06.065) Copyright © 2011 American Society for Reproductive Medicine Terms and Conditions