Developmental changes in the composition and amount of mouse fetal fluids.

Fetal fluid was studied in mice of the Q, C57BL/McL, C3H/Bi/McL and JU/Fa strains. The amount increases to day 16 of gestation, and then decreases. Amniotic fluid and fetal plasma contain three transferrins, five alpha-fetoproteins and albumin. Protein concentration in both increases during gestation; glucose decreases in amniotic fluid although it rises in fetal plasms; urea levels remain constant. The regulation of volume and biochemical composition of amniotic fluid, and its relation to the yolk-sac membrane, are discussed.