Expression of progesterone receptor mRNA in the first trimester human placenta

The human placenta produces large quantities of progesterone, the function and target tissues of action of which during pregnancy are not completely understood. Although it has been suggested that placenta itself could be a potential target tissue for progesterone action, there is no conclusive evidence for the presence of progesterone receptors in the human placenta. We provide evidence for the expression of progesterone receptor mRNA in the human placenta by reverse transcription coupled to polymerase chain reaction (RT-PCR). This was further confirmed by Southern hybridization, restriction analysis and sequencing of the PCR amplified fragment.