The kinetics of 1,2-3H-cortisol after intra-amniotic administration

Foetuses of random-bred H mice (Velax) received on day 13 of foetal development 1,2-3H-cortisol by the intra-amniotic administration, and 10, 20, 30, 60 and 120 min. after drug injection the radioactivity in the amniotic fluid, foetuses and placentae was determined by methanol extraction. The mean value of total radioactivity in the foetuses and placentae attained 2.2% and 2.7%, respectively, of the injected dose during the first 10 min. and did no longer change substantially. Total radioactivity in the amniotic fluid, after an initial acute fall, corresponded to 16.4% of injected dose from 20 min. to 2 hours after drug administration.