THE MISSING LINK IN RHESUS-MONKEY AMNIOTIC-FLUID VOLUME REGULATION - INTRAMEMBRANOUS ABSORPTION

Objective: To investigate whether intramembranous absorption occurs in the rhesus monkey and its role in amniotic fluid (AF) volume regulati on as a possible model for the human fetus. Materials and Methods: We studied five chronically catheterized rhesus monkey fetuses (Macaca mu latta) at 126 +/- 1 (standard error) days' gestation (term approximate ly 165 days) with ligated esophagi and catheterized tracheae. Samples (0.5 mt each) of fetal and maternal blood and amniotic and lung fluid were collected at 0, 15, 30, 60, 120, 180, and 240 minutes after injec tion of 0.1 mCi (3 mL) of technetium-99m (Tc-99m) into the amniotic ca vity. Results: In spite of esophageal ligation, there was a rapid abso rption of the Tc-99m into the fetal circulation within 15 minutes of i njection. The maternal Tc-99m activity increased in parallel to fetal activity but remained lower. The fetal lung fluid Tc-99m activity incr eased more slowly but was equivalent to the fetal circulating level by 4 hours. Conclusions: These results suggest that intramembranous abso rption occurs and map play an important role in rhesus AF volume regul ation and composition. Furthermore, this animal model, which closely r esembles the human, may provide valuable insight into abnormalities of human AF volume regulation. Copyright (C) 1997 by The American Colleg e of Obstetricians and Gynecologists.