values for the concentrations of deoxyribonucleoside triphosphates in rat embryos on day 12 of gestation , determined by high-pressure liquid chromatography , were artifactually two to three times as high in embryos fixed by cooling in ice/water followed by freezing on solid co2 , in 20s , as in those more rapidly/fixed in liquid n2 , in 1 s .
C0020746
ice
C0043047
water