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Using reverse transcriptase and the polymerase chain reaction (PCR) to detect fetal RNA in maternal blood samples may be helpful in identifying RhD-positive fetuses. Reverse transcriptase is an enzyme that converts RNA into DNA. Fetal messenger RNA is much more abundant in maternal blood samples than fetal DNA. Researchers used this technique to detect RhD-positive fetuses in 35 RhD-negative pregnant women. This technique identified more RhD-positive fetuses than traditional PCR tests for fetal DNA in maternal blood. Normally, amniocentesis or chorionic villus sampling is used for prenatal diagnosis, but they can harm the fetus.

A simple technique used to evaluate messenger ribonucleic acid (mRNA) patterns called polymerase-chain reaction appears to provide useful information about changing gene expression in the uterine lining during pregnancy. Uterine lining samples taken from 30 pregnant rats on days 12, 16, 20, 21, 22 of pregnancy and one day after delivery were analyzed using polymerase-chain reaction. More than 500 mRNA sequences were identified. Some sequences were expressed more frequently and some less frequently as the pregnancy advanced.

Leukemia inhibitory factor (LIF) may play a role in early embryonic development and ectopic implantation. LIF is believed to enhance early embryonic cell division, differentiation, and implantation. Researchers measured amounts of messenger RNA (mRNA) for making LIF in human Fallopian tubes and cell cultures of cells from Fallopian tubes removed during ectopic pregnancy. LIF mRNA was found in greatest quantity in the inner surface of the Fallopian tube and was markedly elevated in ectopic pregnancy. LIF mRNA production was stimulated by the substances that mediate inflammation, which suggests linkages among inflammation, LIF, and ectopic pregnancy.

Messenger ribonucleic acid (mRNA) for epidermal growth factor (EGF) receptor appears to be present in the fetal ovary and uterus at different stages of development. EGF receptor is a receptor for both EGF and transforming growth factor-alpha (TGF-alpha). A study examined the presence of mRNA for EGF receptor, EGF and TGF-alpha in fetal ovarian and uterine tissue at 10-, 15-, 19- and 22-weeks of development. mRNA for EGF receptor was found in both ovarian and uterine tissue at all four stages of development. mRNA for TGF-alpha was present in ovarian tissue at all four stages of development, but it was not found in uterine tissue at any stage of development. mRNA for EGF was found in both uterine and ovarian tissue at all four stages of development.

OBJECTIVE: Human placenta expresses receptors for transforming growth factor-[alpha] and epidermal growth factor throughout pregnancy. Experiments were performed to determine whether epidermal growth factor or transforming growth factor-[alpha] might be synthesized by placental cells and act through an autocrine. mechanism to influence functioning of placental cells in vivo. STUDY DESIGN: Human placentas from early, mid, and late gestations were analyzed for transforming growth factor-[alpha] and epidermal growth factor messenger ribonucleic acid and proteins. Polyadenylic acid-positive ribonucleic acid was isolated from placentas from 10, 11, 13, 21, 32, 38, 39, and 40 3weeks of gestation and analyzed by Northern analysis for hybridization with complementar deoxyribonucleic acid probes specific for epidermal growth factor or transforming growth factor-[alpha]. Levels of immunoreactive epidermal growth factor and transforming growth factor-[alpha] were measured by specific radioimmunoassays in pools of placentas from early, mid, and late gestations, and levels of epidermal growth factor and transforming growth factor-[alpha] receptor-active protein were measured by radioreceptor assay. RESULTS: All placentas had a strong transforming growth factor-[alpha] hybridization band at 4.5 kb and a weak epidermal growth factor hybridization band at 5.2 kb. High levels of transforming growth factor-[alpha] immunoreactive protein (90 to 180 ng/mg protein) and low levels of immunoreactive epidermal growth factor (3 to 9 pg/mg protein) were detected in pools of placentas from early, mid, and late gestations. High levels of epidermal growth factor and transforming growth factor-[alpha] receptor-active protein (250 ng/mg protein) were also detected. CONCLUSION: Human placentas contain relatively high levels of immunoreactive and receptor-active transforming growth factor-[alpha], as well as transforming growth factor-[alpha] messenger ribonucleic acid, throughout gestation. This finding suggests that transforming growth factor-[alpha may act by an autocrine system to influence human placental cell function in vivo. (Am J Obstet Gynecoe 1992;166:192-9.)