Induction of iNOS mRNA expression in human fetal membranes (FM) by culturing in the presence of serum for 24 hours. Lane 1 fetal membranes immediately after collection, lane 2 membranes cultured with serum, lane 3 membranes cultured with serum and 1 μM PAF, lane 4 positive control for iNOS, lane 5 PCR blank, M DNA markers. The expected size of the product was 310 base pairs. One example is shown of three identical results with three different samples of fetal membranes. All of the fetal membrane samples were initially negative for iNOS mRNA, as detected by the standard RT-PCR method.