The origin of human placental oxytocinase

1. Placentas from normal women and from those with pre-eclamptic toxaemia, taken immediately after labour, were examined for oxytocinase activity and analysed morphometrically.2. Both enzyme activity and volume of syncytiotrophoblast were significantly reduced in placentas from patients with toxaemia.3. There was a positive correlation between the enzyme activity and the proportion of trophoblast in the placenta. When the activity was expressed per unit volume trophoblast, there was very little difference between placentas, whether from normal subjects or from patients with toxaemia.4. It is concluded that human placental oxytocinase is located in the syncytiotrophoblast.

Oxytocinase in plasma and placenta in normal and prolonged labour

In prolonged labour (dystocia) the level of activity of the enzyme oxytocinase is increased in the plasma and decreased in the placenta; the ratio of its activity in the placenta to that in plasma is less than half that found in normal labour. A possible explanation is that oxytocinase is derived mainly from the placenta and that during prolonged labour the enzyme escapes into the maternal blood stream.

Ion Uptake by Living Plant Roots

By taking daily autoradiographs of a uniformly labeled soil in which plants are growing, patterns of actual ion uptake from the soil can be established. This technique can be used to study such influences on ion uptake as that of plant species ion diffusion, moisture and temperature stresses, and different physical, chemical, and biological properties of the soil.