Temperature curve at freezingThe deposition of 150~pL opened straws at 6.5 cmfrom the surface of liquid nitrogen for 15 min resultedin a linear decrease of temperature from 22 to -60.5 “C(rZ = 0.97) in straws at a cooling rate of 64.9 ‘C.min-’(figure 1). A quite similar temperature profile wasobtained with the protocol designed for 1.5-mL emptycryovials. The cooling rate was 61.0 “C.min-‘. Thetemperature decrease stabilised at -95 “C after 12 min.When the thermocouple was placed into containerswith diluted sperm, the temperature profiles were modified due to cristallisation. The seeding point occurredat 10 s/-5 “C in straw and 12 s/-l I “C in cryovial andthe temperature surges were respectively up to -0.9 “Cand -2 “C. The temperature decrease in cryotube wasslower but more regular than in straw so that thevariations after 3 min (-60 “C) were similar for the different containers. The decrease slowed down to zero at-93 “C and then the temperature remained stable for5 min. The temperature dropped abruptly to -193 “Cwhen straws or vials were dropped into liquid nitrogen.