Fibrinolysis in Human Foetuses

Summary The fibrinolytic system was studied in blood from 74 human foetuses in the 12th to 24th gestational week and with crown‐heel lengths between 10 and 32 cm. Plasminogen could be demonstrated in all foetuses in an amount equal to about 20 per cent of that in adults. There was also a definite plasminogen activator activity and a remarkable fibrinolytic capacity. The α2‐macro‐globulin content was about 30 per cent of that in adults, while progressive antiplasmin was at, and the inhibitors of plasminogen activationabove, adult level. The fibrinolytic system develops early in intrauterine life. Like other enzyme systems essential to life, it must serve some physiologic purpose, presumably to keep the foetomaternal circulation patent.