Abstract
Summary
Mean endogenous progesterone concentrations of bovine luteal tissue increased from 29.2 μg/g at day 8 to 47.2 μg/g at day 16 of the estrous cycle. Δ4 Pregnen-20β-ol-3-one increased from 0.3 μg/g at day 8 to 2.0 μg/g at day 16. Mean progesterone concentration increased 46.2 μg/g in tissue at day 8 of the cycle and 53.4 μg/g in tissue from day 16 during 2 hr incubation in Krebs Ringer bicarbonate medium. Increases of 20β-ol concentration on incubation were 2.1 and 12.4 μg/g at days 8 and 16 respectively. Mean concentration of progesterone ranged from 4.0 to 18.2 μg/g and 20β-ol from 5.3 to 10.5 μg/g in luteal tissue at seven stages of pregnancy investigated. Blood plasma from pregnant animals contained 0 to 2.13 μg progesterone/100 ml plasma and no detectable 20β-ol. Neither progesterone nor 20β-ol was detected in placental fluids and only progesterone (4.4 μg/kg) was found in one of 6 placentae.
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