DDX4 and Wilms tumor: The reproducibility of the optimal freezing (containing 35.2% extender, 1.3 M Me2SO, 0.1 M trehalose and 1.5% BSA) and vitrification protocols (containing ES1: 1.5 M MeOH and 1.5 M PG and VS3: 3 M PG and 3 M Me2SO) was tested by cryopreserving whole testes of six different zebrafish lines (AB wild-type, casper (mitfaw2/w2; mpv17a9/a9), leopard (gja5bt1), vasa::egfp (ddx4sa6158/sa6158) transgenic line, Wilms tumor::egfp (wt1b) transgenic line and β-actin:yfp (pku341Tg) transgenic line).