[Studies on prolyl hydroxylase activity, hydroxyproline content and solubility of collagen in the human uterus during pregnancy, delivery and postpartum involution (author's transl)].

Prolyl hydroxylase activity, hydroxyproline content and solubility of collagen in the human pregnant and post-partum uterus were studied. The results were as follows: 1. Prolyl hydroxylase activity in the uterine cervix was slightly elevated during pregnancy, and the highest level was observed on the 4th day post-partum. On the other hand, in the uterine body the highest activity was observed immediately after delivery. 2. Hydroxyproline content in the pregnant uterine cervix was slightly less than that of nonpregnant control and the lowest level was observed immediately after delivery, but on the 4th day post-partum it increased slightly. In the uterine body, there were no remarkable changes in content during pregnancy, but immediately after delivery it decreased remarkably. 3. Pepsin-soluble collagen in the uterine cervix increased significantly from an early pregnancy to immediately after delivery compared with nonpregnant control, but on the 4th day post-partum it decreased significantly compared with that immediately after delivery. In the uterine body, no significant changes in solubility were observed throughout pregnancy. 4. Comparing these data obtained on the cervix and the body at different stages of nonpregnancy, pregnancy and post-partum, enzyme activities in the body were always higher. Hydroxyproline content in the body of nonpregnant uterus showed a lower value than that in the cervix, but no remarkable differences were found between the cervix and the body throughout pregnancy and immediately after delivery. The significant decrease in pepsin-soluble collagen in the body was observed immediately after delivery.