Concentrations of oxytocin in the plasma and amniotic fluid of rhesus monkeys (Macaca mulatta) during the latter half of pregnancy.

A specific radioimmunoassay for oxytocin has been established with a sensitivity of 0.8 pg/tube. This assay has been applied to the measurement of oxytocin in serial samples of peripheral plasma and amniotic fluid from pregnant rhesus monkeys, collected at weekly intervals by venepuncture and amniocentesis. Concentrations of oxytocin in both fluids were generally low and showed no trends throughout the latter half of gestation.