Method for preservation of water content during prolonged storage of cerebral tissue

We set out to determine whether prolonged freezing of samples of cerebral tissue would alter specific gravity measurements. Our goal was to devise a method to prevent tissue water evaporation during transportation and storage of human cerebral samples in order to allow accurate measurements of specific gravity and water content at a delayed time. Control cerebral samples from healthy and water-intoxicated anaesthetized adult mice were immediately immersed in a gravimetric column for fresh specific gravity measurements. Cerebral samples from the same animals were also preserved by rapid freezing in liquid nitrogen, followed by deep-freeze storage at -80 degrees C for up to 7 days. The mean specific gravity and standard error of 65 non-oedematous and 18 oedematous fresh cerebral samples was 1,0483 +/- 2 x 10(-4) and 1,0433 +/- 5 x 10(-4), respectively. Freezing for 1 h to 7 days resulted in no significant alteration of specific gravity for 109 non-oedematous and 27 oedematous samples (P greater than 0.05). We describe a rapid freezing technique that is practical for transportation and storage of experimental or surgical cerebral specimens. Our findings indicate that storage of cerebral samples in liquid nitrogen, with or without subsequent deep-freezing, preserves water content of normal and oedematous cerebral tissue, thereby allowing accurate measurements at a later time.