Improved solution for vitrification of <italic>Prochilodus lineatus</italic> embryos based on the reduction in risk factors: Toxicity, osmotic responses and ice‐nucleation.

Abstract: The objective of our work was to describe a low toxicity cryoprotectant solution that allowed vitreous solid formation. Embryos of <italic>Prochilodus lineatus</italic> were submitted to sensitivity evaluations of six internal cryoprotectants (dimethyl sulphoxide – Me₂SO, dimethyl acetamide – DMA, dimethyl formamide – DMF, methanol – MET, glycerol – GLY and 1,2‐propanediol – PROP) at concentrations of 1–6 M; and two external cryoprotectants (sucrose – SUC and glucose – GLU) at concentrations of 0.1–1 M for 20 min. The capacity of the cryoprotectant solutions to exchange heat with the medium and to form glassy solids was evaluated by immersing 10 μl of cryoprotectant in liquid nitrogen. The PROP had a high survival rate at all concentrations evaluated, and was the only substance that allowed a vitreous solid formation. Thus, it is concluded that the PROP‐6 M was the most adequate solution for embryonic vitrification processes, because heat exchange between the system (PROP 6 M/embryos/liquid nitrogen) was faster than for other cryoprotectants and combinations thereof; has low toxicity, promote high rates of dehydration in short periods, and reach the vitreous state, being a good candidate to be used in the tests of embryonic vitrification. [ABSTRACT FROM AUTHOR]