Gestagens in peripheral, uterine, ovarian and fetal blood in cows near term.

The aim of this study was to determine if bovine placenta is capable of producing the gestagen metabolites in vivo. The concentrations of 5 beta-pregnane-3 alpha-20 alpha-diol, 17 alpha,20 alpha-dihydroxyprogesterone and progesterone were measured by HPLC-RIA in samples obtained after surgical preparation from peripheral, uterine, fetal and ovarian blood of seven cows near term. Measurement of arterio-venous differences in maternal uterine and umbilical circulation confirmed the placental origin of 5 beta-pregnance-3 alpha,20 alpha-diol and 17 alpha,20 alpha-dihydroxyprogesterone, but not progesterone itself. 5 beta-pregnane-3 alpha,20 alpha-diol was preferentially secreted into the fetal compartment. The present experiment, according to earlier in-vitro studies, confirms that the preterm bovine placenta is qualified for in-vivo utilization and secretion of gestagen metabolites.