Determination of the specific gravity of human pineal.

Specific gravity values for the pineal gland in any species are lacking. These data are necessary for calculating and interrelating pineal weight and volume. This report deals with the specific gravity of human pineal gland. The specific gravity of fresh, unfixed human pineal has been determined to be 1.197 +/- 0.036 SEM at 20 degrees C (N = 11) using water as the measuring medium. By contrast, human brain has been reported in the literature to have a specific gravity of 1.036. Specific gravities of human pineals fixed in Bouin's fluid, Bouin's fluid followed by 80% ethanol, 80% ethanol, and embalming fluid were found to be 1.113 +/- 0.025 (N = 5), 0.941 +/- 0.009 (N = 5), 0.990 +/- 0.022 (N = 3), and 1.149 +/- 0.021 (N = 7), respectively. These are corrected values accounting for the specific gravities of the respective measuring fluids. It is shown that the specific gravity of human pineal as derived in this study is directly applicable to calculations of pineal volumes and weights not only in humans, but in other species as well.