Evidence for the placental origin of hyaluronidase in the maternal circulation

The level of maternal serum hyaluronidase activity was shown to rise during pregnancy. Investigation of non-pregnant females did not demonstrate hormonal control of enzyme activity. The findings of a quantitative increase in serum hyaluronidase activity during pregnancy is presented in conjunction with previous evidence of a qualitative change in this enzyme as evidence for a placental origin of the increased activity demonstrated.