Fig. 1.

Images of human Days 5 and 6 blastocyts before vitification (a, b, c) and after vitrification and waming with the Vit-Kit–direct plunge protocol (d), the Fast Freeze–direct plunge protocol (e) and the Fast Freeze −100 °C step protocol (f). After 24 h in culture, all corresponding blastocysts had re-expanded (g, h, i). Respective fluorescent live/dead stained human blastocysts 24 h after warming and culture (j, k, l). Cells with blue nuclei were intact and cells with pink/red nuclei were lysed