Evidence for fibrinogen synthesis and secretion by rat foetal hepatocytes

Fibrinogen concentration in rat foetal plasma is very low at 18 days of gestation but increases rapidly thereafter. The present study provides evidence that this increase is due to synthesis by the foetus itself. (1) 125I-labelled human fibrinogen, injected intravenously into the pregnant adult, did not reach the foetal circulation; (2) turpentine administration to the adult induced an increased maternal plasma fibrinogen concentration without affecting the foetal one; (3) conversely, in utero administration of turpentine to foetuses increased their plasmas fibrinogen concentration without affecting the maternal one; (4) using sheep anti-rat fibrinogen antibodies labelled with peroxidase, in electron microscopy, fibrinogen was located in foetal hepatocytes within the organelles known to be responsible for the synthesis and the ultimate secretion of the protein.