Hl. Hedriana et al., CHANGES IN BLOOD-FLOW TO THE OVINE CHORION AND AMNION ACROSS GESTATION, Journal of the Society for Gynecologic Investigation, 2(6), 1995, pp. 727-734
OBJECTIVE: The purpose of this study was to determine the developmenta
l changes in blood flow to the network of fetal microvessels in ovine
chorion and amnion. METHODS: Colored microspheres (15.10 +/- 0.02 [sta
ndard deviation] mu in diameter) weve infused into the superior vena c
ava in nine chronically catheterized fetal sheep with gestational ages
ranging from 103-141 days (term 147). After euthanasia, chorion, amni
on, and cotyledons were separated and microspheres were counted to det
ermine blood flow rater. Standard correlation and regression analyses
were used to analyze the data. RESULTS: Chorionic blood flow rate incr
eased linearly (r = 0.82, P = .006) from 12 mL/minute at 103 days' ges
tation to 70 mL/minute at 141 days, and averaged 10.3 +/- 1.2% of the
total umbilical blood flow. Weight-normalized chorionic flow (18.4 +/-
2.0 [standard error] mL/minute/kg of fetus) did not change significan
tly across gestation. Absolute and weight-normalized blood flow to the
amnion (0.82 +/- 0.31 mL/minute and 0.34 +/- 0.11 mL/minute/kg fetus)
increased with advancing gestation until 130 days and declined therea
fter. Absolute cotyledonary blood flow rate increased with gestational
age (r = 0.81, P = .008), and weight-normalized cotyledonary blood fl
ow decreased with advancing gestation (r = -0.89, P = .002). Absolute
but not weight-normalized chorionic and cotyledonary blood flow rates
correlated positively. CONCLUSIONS: Blood flow to the microvascular ne
twork in the ovine chorion is high and increases with advancing gestat
ion. Blood flow to the amnion is low but not insignificant. Therefore,
intramembranous exchange may play an increasingly important role in d
etermining amniotic fluid volume and composition as gestation proceeds
.