ENDOCRINE CORRELATES OF PLACENTAL PERMEABILITY DURING GESTATION IN THE PIG

1. Hormone and electrolyte concentrations were determined in amniotic and allantoic fluid collected from sows at 47-112 days of gestation an d correlated with placental and fetal membrane electrolyte permeabilit y. 2. Significant differences between the electrolyte and endocrine ge stational profiles of amniotic and allantoic fluid were identified. 3. The principal endocrine correlate (r > 0.62; P < 0.01) of gestational changes in the sodium and chloride permeabilities of the porcine plac enta and fetal membranes was found to be the concentration of oestroge n in the amniotic fluid.